130 SUPER SPORT: Adding Aft Cockpit Sump

[Jpopsbronco]

Give me ideas on how I could create an aft cockpit sump on a [UNSPECIFIED MODEL YEAR] 2018 130 SUPER SPORT by using the pre-molded sump compartment shown in Figure 1 in the most clean manner, and where it should be located.

Fig. 1. A pre-molded sump area that is to be installed into the Unibond hull of a 130 SUPER SPORT in an unspecified location near the cockpit deck-transom joint line.

sump.jpg (50.73 KiB) Viewed 2163 times

Q1: how can the pre-molded sump be aligned with the cockpit deck?

Q2: how can the pre-molded sump be bonded to the hull?

I am nervous about creating poorly filled screw fastener holes or having the gel coat looking like a whack job.

BACKSTORY
Ever since I have owned my [UNSPECIFIED MODEL YEAR] 2018 130 SUPER SPORT I’ve had wet feet because of the water [that continually] collects in the cockpit. [According to some unspecified source the proper procedure to remove the water is ] to pull [some unspecified] plug while underway for the water to drain--but your feet are already wet at that point. My particular 130 SUPER SPORT has a static trim with the plug just below the line, and, while it will not sink, a ton of "stuff" will grow in the shallow pool of saltwater on the cockpit deck.

I made the sump area pocket [seen in Figure 1]. but I’m not sure the best way to [install it into the deck of the 130 SUPER SPORT Unibond hull].

Note: the cockpit deck in that area has a non-skid pattern in the gel coat.

I have read conflicting information about the use of stringers on these newer-style hulls.

I’m open to [locating the pre-molded sump area] at any spot along the transom.

I was thinking the procedure would be:

1. round the corners [of the pre-molded sump];
2. transfer that shape to the location I choose [on the cockpit deck];
3. precisely cut out a matching portion of the deck gel coat and laminate;
4. dig out the foam;
5. pray I don’t hit stringer or embedded support; and
6. drop in the pre-molded sump.

[Moderator's note: when describing a particular Boston Whaler boat, please give the MODEL YEAR, the FAMILY, the LENGTH, and if transom variations were available, the transom type.]

[jimh]

The modification you propose will involve cutting out a portion of the Unibond hull at the very aft end of the cockpit. The section of the hull liner mold at the aft end of the cockpit deck and the inboard face transom is an important part of the hull structure. Before you starting cutting out a section of that area, you need to know what is below the surface. You could be creating weakness in the transom.

If you have the MODEL YEAR identification for your 130 SUPER SPORT, you could locate several drawings that show some details of the hull construction by visiting the Boston Whaler Owner's Resources page.

See the REFERENCE article at

Drawings of Boston Whaler Components Available Online
https://continuouswave.com/whaler/refer ... wings.html

and read under the sub-heading "Resources for Newer Boston Whaler Boats."

[jimh]

Provide more details:

Q3: where is the hull drain located that you refer to as needing to have a drain plug removed while underway in order to drain water off the cockpit deck?

Q4: how many through-hull or through-transom drains are in this unidentified model year 130 SUPER SPORT?

[jimh]

Just at first glance, the "sump" shown in Figure 1 looks to be too deep. I would seriously review the need for so much depth. You should determine precisely how much space there is between the hull bottom and the cockpit deck at the transom-cockpit deck joint area.

[Jpopsbronco]

Jimh - Thank you kindly for patiently guiding my first post and making it more clear. I really appreciate your input here too. I'll use my pc to post from now on, my initial post was from my iphone and its very challenging workflow to get the images and all formatting nice on the phone.

Here is the thru-hull with drain plug I'm complaining about. The waterline without anyone in it at the dock is even with the top of the thruhll flange. Pulling the plug while moving seems to be the consensus from other owners of this model and engine package to get it to drain, but I think that is stupid.

Fig. 2. Red line points to a through-hull drain in the transom.

IMG_60981.JPG (30.71 KiB) Viewed 2121 times

Here is the interior shot of the same thru hull

Fig. 3. Red line points to a through-hull drain in the transom.

IMG_60991.JPG (27.96 KiB) Viewed 2121 times

And here is the approx. position of the sump relative to the hull. There is about an inch clearance between corners of the sump and the hull although it is hard to tell from photo.

Fig. 4. The proposed cockpit sump held against the transom outside the boat to show the relationship of the depth of the sump to the hull.

IMG_6100.JPG (26.31 KiB) Viewed 2121 times

Good question on the depth of the sump. I made it deep enough to house a standard bilge pump and place a cover over the top of it. I think if it is left proud on the deck someone or something will eventually smack it, and I like the look of a clean deck.

[Jpopsbronco]

Just got done looking through the resources in the link you have provided. Thanks for that, they are very useful and I have saved them for later. The only reference I can find to the drain plug is storing on the trailer, nothing about in the water.

I'll also address the elephant in the room: I was obviously concerned about water intrusion making the hull heavy, but I don't believe that is the concern, as I have compared my boat with others of the same make and model and we have the same waterline. My lil vessel has a 25 gallon fuel tank which does not help.

It is what it is, the waterline is where it is. and I need some way besides my damn hand pump to get the water out.

What I think I'm going to do is:

1. center the sump on the transom since that seems to be the best place for it;
2. cut out my hole, remove foam;
3. carefully sand off a 1-inch-wide strip of the nonskid around the cutout;
4. attach backing blocks on the underside of the floor with thickened resin;
5. use thickened resin and also fiberglass to bond the sump in place;
6. though small hole in sump, refill hull with pour foam;
7. sand fair and flat;
8. brush gel coat on and wetsand, buff to gloss.

I know it seems crazy to chop a hole in this nice boat's floor, but I bought it to use it, not to look at it.

[Jefecinco]

A factor you may want to consider before proceeding with your plan is what such an ill conceived modification will do to your boat's value. When the time comes for your boat to be sold why would someone buy it instead of a like unmodified boat. Then only reason will be that it is priced well below the similar unmodified offerings.

[Jpopsbronco]

A factor you may want to consider before proceeding with your plan is what such an ill conceived modification will do to your boat's value. When the time comes for your boat to be sold why would someone buy it instead of a like unmodified boat. Then only reason will be that it is priced well below the similar unmodified offerings.

Thanks for your input. Please share why you think it is ill-conceived? That would be very helpful and could improve my finished result.

[jimh]

In Figure 4 I see that you have positioned the top of the proposed new sump compartment to be at a level which is even with the top of the anti-fouling paint. But the anti-fouling paint is most likely located somewhat higher than the actual water line of the hull, especially at static trim. A better reference for the vertical positioning is the outlet of the aft cockpit through-transom drain (as identified in Figures 2 and 3.)

Because that drain uses plastic fittings at both ends, I am assuming that the drain is drilled at right-angle to the transom. If that is correct, then the bottom of the drain is just about tangent to the cockpit deck level.

When viewing Figure 4 with those relationships in mind, the top surface of the proposed sump area is clearly going to end up being higher than the cockpit deck. Or, at least, that is how it appears in the photograph.

Also, even if the vertical position of the proposed sump is properly aligned so its top will be flush with the deck, the bottom of the sump looks like it will be very close to the hull bottom.

The stiffness of the Unibond hull depends greatly on there being a continuous bond between the hull-bottom laminated part, intervening foam, and the hull-liner laminated part. The lamination schedule of neither laminated part is not particularly thick or particularly strong once the solid foam that is strongly bonded to each laminate is removed.

On that basis, the proposed sump area as defined by the pre-made part you are holding in your hand in Figure 4 seems like it will be too deep to properly fit level with the deck and not required removal of practically all the foam in the hull in that area. Also, once you put the pre-molded sump in place, you won't have any way to fill air pockets and voids with foam that are probably going to exist--unless foam removal is extraordinarily precise.

You might consider approaching the problem with a passive drain system instead of using an electric pump. One way to approach that is to create a slight depression in the cockpit deck, perhaps a U-shape with the open part of the U facing the transom. You could cut out a matching area of the deck. then sculpt away the foam so the depth of removed foam increases toward the center of the U-shape. The depth does not need to be great, just enough to hold some water until it can drain out via a new path to be created. Then laminate a layer or two of cloth and resin to cover the foam using epoxy resin and suitable cloth, and when fully cured blend that into a smooth joint with the original deck level. Finally, drill a hole through the bottom of this shallow sump, vertically downward, and through the foam, all the way through the hull bottom. Into this hole install an old-fashioned brass tube drain with rolled edges.

The sump should collect all the water in the cockpit. Leave the through-transom drain plugged. As long as the deck level is above the water line, the water will drain off the deck into the sump, and then out the new open drain to the sea.

But the essential element of all this is the cockpit deck level at the transom area must be above the water when the boat is at static trim. Otherwise, adding another drain (through the hull bottom) will just let more sea water come aboard.

[jimh]

Also important to note:

If the through-transom drain already on the boat is letting sea water come aboard, then your plan to add a sump to hold the sea water and let a pump move it back to the sea is really going to become a continuous machine trying to pump the seawater over the transom and back to the sea, unless you close the existing drain. But if the existing drain is closed, then there would not be any water from the sea collecting in the cockpit. The only water would be rain water or perhaps some spray that comes aboard.

Also regarding using a centrifugal pump: these pumps cannot prime themselves. The must always be located in a sump and have their rotating vane element submerged. This also means they can never get all the water out of the sump. They will always leave about a half-inch or more of water in the sump.

A different type of pump that can self-prime and suck water into its inlet, pulling the water upward into the pump mechanism, will be able to remove water in a sump to a very low level, basically sucking it dry. Depending on how far vertically a particular pump can lift water, you could make a much shallower sump, and locate the pump on the transom, with its intake hose extending downward into the shallower sump. Here is an example:

https://seaflodirect.com/seaflo-02-seri ... -12v-8gpm/

[jimh]

Another observation:

The pump you show in your illustration is marked as having a flow rate of 750-GPH, which is 0.21-gallons-per-second. This means that if the sump holds one-gallon of water, your pump will evacuate the water in 4.8-seconds. From that I infer that you really want to get that damn water out of the boat in a hurry. :-)

[NorthShoreWhaler]

I have a 150 Super Sport with the same drain system. My advice: do not install a sump, but instead get a manual bilge pump and remove the water after putting in the drain plug and boarding.

[Jefecinco]

jpopsbronco - There are so many reasons, but the primary one is interference with the structural integrity of the hull. The several reasons discussed by jimh in the posts following your last post sum them up very well.

I would categorize your plan as experimental surgery on a patient not suffering an ailment. I suspect you would support the fact that since Boston Whalers engineers have not made a significant change to this hull for many years they don't believe a change is needed.

You seem determined to proceed with your plan. Please let the community know how it works out for you.

[Jpopsbronco]

I have a 150 Super Sport with the same drain system. My advice: do not install a sump, but instead get a manual bilge pump and remove the water after putting in the drain plug and boarding.

I have a manual bilge pump now, and stand in a little water to pump it out. If I pull the plug at the dock, water comes rushing in.

[Jpopsbronco]

jpopsbronco - There are so many reasons, but the primary one is interference with the structural integrity of the hull. The several reasons discussed by jimh in the posts following your last post sum them up very well.

I would categorize your plan as experimental surgery on a patient not suffering an ailment. I suspect you would support the fact that since Boston Whalers engineers have not made a significant change to this hull for many years they don't believe a change is needed.

You seem determined to proceed with your plan. Please let the community know how it works out for you.

Okay, thanks. I probably will, but thanks to Jim's input my plan is now better than when I started.

I get that you don't think it is a problem, or that big of a problem. This one is a 2024, can you guess why he mounted his pump to the floor? It's because he likes to stand in 1/2" of water.

Fig.5. New 130SS with Bilge Pump Installed per Jefecino Logic

40A5EA8A-E399-43AE-B1E7-EAB131B286EA.jpg (53.75 KiB) Viewed 1925 times

Maybe other whalers are different. I don't know. I do know that this whaler isn't a collectible or anything special, so I'm gonna 3d print another mold for my revised sump and show you guys how it turns out when I finish.

[Jpopsbronco]

Also important to note:

If the through-transom drain already on the boat is letting sea water come aboard, then your plan to add a sump to hold the sea water and let a pump move it back to the sea is really going to become a continuous machine trying to pump the seawater over the transom and back to the sea, unless you close the existing drain. But if the existing drain is closed, then there would not be any water from the sea collecting in the cockpit. The only water would be rain water or perhaps some spray that comes aboard.

Also regarding using a centrifugal pump: these pumps cannot prime themselves. The must always be located in a sump and have their rotating vane element submerged. This also means they can never get all the water out of the sump. They will always leave about a half-inch or more of water in the sump.

A different type of pump that can self-prime and suck water into its inlet, pulling the water upward into the pump mechanism, will be able to remove water in a sump to a very low level, basically sucking it dry. Depending on how far vertically a particular pump can lift water, you could make a much shallower sump, and locate the pump on the transom, with its intake hose extending downward into the shallower sump. Here is an example:

https://seaflodirect.com/seaflo-02-seri ... -12v-8gpm/

Jim - thanks again for all your input. You'll just have to trust that I'm not dumb enough to leave the plug out. And also trust that I know how to measure haha!

In my big boat I use plenty of the diaphragm pumps, I'm quite familiar. They need great filters, and do not last in an exposed environment. They are commonly used in dry bilge setups and draw tiny amounts of water through sponges and then through filters. They are also very large, and cannot be submerged. I did briefly consider one but couldn't conceive of a reliable float switch that I thought would last and turn on at .25" of water.

I didn't get the spoon fed "do this this and this" I was hoping for, but I was able to draw some nuggets out of the replies. I'll post back after I make some headway. If you never hear back, it's because my transom snapped off and my unsinkable boat sunk with me on it :-)

[jimh]

The centrifugal pump seen in Figure 5 was probably mounted on the starboard side because the helm is also on starboard, so the boat probably has a list to starboard when the helmsman is sitting at the helm, keeping the cockpit water toward starboard.

The battery is not in view. Because the engine cables are all carried forward, I suspect the battery is under the helm seat. There appears to be a fuel tank in view on the port side under the helm seat. The battery is likely to be on the starboard side under the helm seat. That weight distribution further tends to put the trim to be a list to starboard.

The engine cable rigging is well done as it keeps the cables clear of the cleat fittings. Compare with Figure 1.

The boat seen in Figure 5 appears to be on display at a boat show. Perhaps the pump at the transom was a factory option or maybe a dealer-installed improvement.

[Jpopsbronco]

The centrifugal pump seen in Figure 5 was probably mounted on the starboard side because the helm is also on starboard, so the boat probably has a list to starboard when the helmsman is sitting at the helm, keeping the cockpit water toward starboard.

The battery is not in view. Because the engine cables are all carried forward, I suspect the battery is under the helm seat. There appears to be a fuel tank in view on the port side under the helm seat. The battery is likely to be on the starboard side under the helm seat. That weight distribution further tends to put the trim to be a list to starboard.

The engine cable rigging is well done as it keeps the cables clear of the cleat fittings. Compare with Figure 1.

The boat seen in Figure 5 appears to be on display at a boat show. Perhaps the pump at the transom was a factory option or maybe a dealer-installed improvement.

its pre owned, battery and fuel tank are both to port. I doubt a dealer would install a bilge pump unless a sale depended on it. My point with that image was if the hull is perfect and the concern I describe is imagined, this person must also be imagining things. There are plenty more of these 130SS models with bilge pumps lackadaisically thrown on the deck...

https://www.morganmarine.net/default.as ... r=1&img=15

My question was never about whether I should or should not, not sure why everyone took it that direction. My hope was that people on this forum had experience working on these boats and could share insight into the pitfalls and gotcha's when going below deck, and maybe some suggestions for how to tab in the sump to the floor cleanly. You've gotten the closest to answering that, with your opinion about my weakening the structure, which I thank you for.

[Jpopsbronco]

The creation of a new cockpit sump area and its addition to the hull of the 130 SUPER SPORT is shown below in several posts.

I began by designing the plug-mold for the bilge pump sump in CAD, and then 3D printed the plug of the mold out of ABS. I coated it in PVA and used a mix of chopped strand and cloth to build up the part in the mold to get the thickness to surpass the floor thickness.

Fig. 6. A 3-D printed ABS mold, semi faired out and covered in PVA3

IMG_6067.jpg (133.44 KiB) Viewed 1318 times

Fig. 7. The thickness of the molded sump part compared to the laminate thickness of the deck that was cut out.

IMG_6133.JPG (69.06 KiB) Viewed 1318 times

I cut out the floor and removed the foam so the sump box would fit nicely.

​​​​​​​

Fig. 8. The laminated sump and the cut out section of deck with interior foam removed.

IMG_6135.JPG (93.59 KiB) Viewed 1318 times

[Jpopsbronco]

I undercut the foam under the floor so I could fit 3/4-inch-thick black Coosa board. The Coosa is laid in so half is under the deck and will be under the lip of the sump box. The Coosa board was adhered with a lot of thickened resin and glass.

Fig. 9. Coosa board reinforcements in cut out area.

IMG_6155.JPG (120.25 KiB) Viewed 1318 times

I bonded-in the sump box with more thickened resin. While hard to tell, the whole aft portion of the sump box is flat, and bonded to the transom, and the sides were bonded vertically and horizontally to the Coosa board.

Fig. 10. The sump box bonded to the hull. The object sitting the sump [is not identified but perhaps is a weight].

IMG_6157.JPG (92.3 KiB) Viewed 1318 times

Fig. 11. The sump box joint to the deck and transom was deepened to a V-shape; chopped strand and cloth with resin holds everything together.

IMG_6165.JPG (90.65 KiB) Viewed 1318 times

[Jpopsbronco]

I started getting the mating surfaces flat, using gel coat to see where my low and highs were:

Fig. 12. The start of fairing the joint between the new sump and the hull.

IMG_6185.JPG (94.14 KiB) Viewed 1317 times

And repeated the gelcoat - sand flat process a few times, and going further outward each time until I reached my tape line for the transition to nonskid

Fig. 13. The joint line is now all gel coat resin and flat.

IMG_6189.JPG (112.03 KiB) Viewed 1317 times

Then I wet-sanded and polished the gelcoat to match the rest of the boat's shine. I tinted the last few coats of gel coat to match the deck color. I think I did a decent job.

Fig. 14. While a poor picture and the boat is very dirty, the gel coat match between the original and new part is good.

IMG_6201.JPG (74.9 KiB) Viewed 1317 times

[Jpopsbronco]

As a final steop, I 3D-printed a cover. Then I gave the boat a good cleaning. I am happy with how it came out.

When you whack the new sump part, the sound is dead, not hollow at all. I noticed this after the part was just bonded-in, before the fiberglass joint was added.

Although I had 6-lbs density foam on hand, I opted not to use after I realized how strong this new part was. I felt using foam was unnecessary, and there was no reason to risk overfilling and bulging the surrounding floor.

Fig. 15. The new cover in place and a clean cockpit.

IMG_6308.JPG (71.67 KiB) Viewed 1317 times

Fig. 16. The sump pump installed in the new cockpit sump and an output hose rising over the transom.

IMG_6309.JPG (60.97 KiB) Viewed 1317 times

The setup works really well for cleaning--even in the driveway, I used to dread cleaning the cockpit. The boat is much more livable with the water automatically exiting. The rear gutter works beautifully with this sump, all the water drains into the sump and doesn't collect anywhere else.

Fig. 17. The sump pump working to remove water.

sumpPumpWorking.jpeg (20.33 KiB) Viewed 1268 times

PROJECT SUMMARY

I had quite a few other boat projects going with this little sump box; fishfinder, underwater lamps, engine service, bottom paint, gelcoat repair. All of it took me about a month to finish, but I'd estimate the sump box took me about a week to do, and that was with me stepping back at each phase and scratching my head before moving to the next.

This modification should solve the annoying problem of water pooling in the stern of the cockpit of the 130 SPORT.

[Kapharms]

Looks fantastic. Very nice work

[jimh]

Your modification was extremely well done. I doubt that anyone could tell the 130 SUPER SPORT didn't come from the factory like that.

Your skill with fabricating the new molded part, modifying the hull, and joining the new part to the hull was very admirable. I doubt that many could accomplish that as well as you did.

It is a very interesting modification, well done, and very nicely documented. Thanks for this excellent addition to the knowledge base here.

[jimh]

Referring to Figure 9:

Q5: is that red resin seen on the transom side of the newly created hole the original resin used by Boston Whaler?

Q6: is the tan-colored putty on the transom side of the newly created hole also original to the Boston Whaler assembly of the hull?

Q7: when creating the new cavity in the foam and hull of the boat for the new sump, did you remove all the foam all the way down to the laminated hull bottom?

Q8: is there an air gap between the bottom of the new sump compartment and the hull bottom?

[Jpopsbronco]

Looks fantastic. Very nice work

Thanks. We'll see how she hold up but I think I overbuilt it.

[Jpopsbronco]

Q5: is that red resin seen on the transom side of the newly created hole the original resin used by Boston Whaler?

Yes, that is the factory resin.

Q6: is the tan-colored putty on the transom side of the newly created hole also original to the Boston Whaler assembly of the hull?

The tan color is the factory foam.

Fig. 17. More details of the modification: CALLOUT 1 is the blue-green 3M Vinylester structural filler which I used to bond the Coosa Board and make fillets so the glass cloth can lay nicely; CALLOUT 2 is the glass cloth tying the Coosa Board to the hull bottom.

Screenshot 2025-08-05 1100261.jpg (83.32 KiB) Viewed 1246 times

Q7: when creating the new cavity in the foam and hull of the boat for the new sump, did you remove all the foam all the way down to the laminated hull bottom?

Yes. In Figure 18 there is a better picture of the inside of the hull bottom with some more descriptions.

Fig. 18.More details of the hull and the removed foam: CALLOUT 1 is thickened resin that I assume the factory used to increase the strength and thickness of the keel; CALLOUT 2 is the inside of the hull bottom. I estimate it to be between 1/4 and 5/16-inch thick; CALLOUT 3 is a bulbous section which I believe adds strength to the area where the transom and keel meet.

Screenshot 2025-08-05 1058581.jpg (83.17 KiB) Viewed 1246 times

Q8: is there an air gap between the bottom of the new sump compartment and the hull bottom?

Yes, I left an air gap rather than backfilling with pour foam. I felt things were more than strong enough and the foam in this area wouldn't add anything. I didn't want to risk having a situation where the pour foam bulges the floor due to over filling and/or too small of vent holes. The lip of the sump box was ground down to match the floor thickness of 1/8", but the rest of the sump box was between 3/16 and 1/4" thick.

Summary of laminate layer thickness

Hull bottom: 1/4 to 5/16-inch thick in most areas, with reinforcement in areas of high stress or high likelihood of impact
Deck fiberglass section: 1/8-inch thick
Deck gel coat section: 1/16-inch thick (including thickness of raised non-skid)

[Jpopsbronco]

I will also add that the factory foam is "nice". Compared to some other pour foams I played with, the factory foam has more tendency to flex before breaking. The size of the bubbles is smaller and very uniform too. It was well bonded to the factory section of the cockpit that I cut out. After I had this huge hole cut out, but before I started adding the Cooosa Board and stiffening it, I flexed the surrounding floor and could see the deflection taking place, which the foam happily absorbed and sprung back from.

Just some more anecdotal information.

[jimh]

The addition of Figures 17 and 18 adds much interesting information to the narrative. Thanks for the further exposition of the work.

My initial hesitancy to endorse or my criticism of making this modification was done without knowing the fantastic skill set possessed by the guy who would make the modification, Jpopsbronco, and who was able to:

• design a new sump part;
• model the sump in a CAD file;
• print the part on a 3D printer;
• create a male plug mold from the 3D printer output;
• spray color-matched gel coat resin onto the plug;
• build up more layers of cloth laminations to a chosen specific thickness;
• successfully separate the part from the plug;
• fearlessly tear into a Unibond hull and create a closely matched new cavity;
• very successfully install the part into the cavity;
• blend the new part into the existing deck with excellent cosmetic results;
• and create a very useful addition to the 130 SUPER SPORT.

I didn't know in advance that this proposed modification was going to be designed by a modern Leonardo da Vinci.

If I had known, I probably would have been more receptive to the idea proposed. :-)

[jimh]

ASIDE

I will also add that the factory foam is "nice". Compared to some other pour foams I played with, the factory foam has more tendency to flex before breaking.

Your observation is actually very interesting. I have played with some Unibond hull cross sections that were cut outs given to dealers to display to show the nature of the Unibond hull, and the foam in those samples did not exhibit any resiliency or rebound from compression.


Fig. 19. A dealer showroom boat with a sample cross section of a Unibond hull seen in c.2005.

I suspect that the foam in the cross-section sample has contracted somewhat since its originally being cut out of the hull. I would have expected the foam edges would have been straight lines, and they are now indented curves. But perhaps that came from too many people handling them.

But I would not have described the foam as having resilience and able to rebound from compression.

[Jpopsbronco]

The addition of Figures 17 and 18 adds much interesting information to the narrative. Thanks for the further exposition of the work.

My initial hesitancy to endorse or my criticism of making this modification was done without knowing the fantastic skill set possessed by the guy who would make the modification, Jpopsbronco, and who was able to:

• design a new sump part;
• model the sump in a CAD file;
• print the part on a 3D printer;
• create a male plug mold from the 3D printer output;
• spray color-matched gel coat resin onto the plug;
• build up more layers of cloth laminations to a chosen specific thickness;
• successfully separate the part from the plug;
• fearlessly tear into a Unibond hull and create a closely matched new cavity;
• very successfully install the part into the cavity;
• blend the new part into the existing deck with excellent cosmetic results;
• and create a very useful addition to the 130 SUPER SPORT.

I didn't know in advance that this proposed modification was going to be designed by a modern Leonardo da Vinci.

If I had known, I probably would have been more receptive to the idea proposed. :-)

I'll take a compliment where I can :) Thanks!

ASIDE

I will also add that the factory foam is "nice". Compared to some other pour foams I played with, the factory foam has more tendency to flex before breaking.

Your observation is actually very interesting. I have played with some Unibond hull cross sections that were cut outs given to dealers to display to show the nature of the Unibond hull, and the foam in those samples did not exhibit any resiliency or rebound from compression.

I suspect that the foam in the cross-section sample has contracted somewhat since its originally being cut out of the hull. I would have expected the foam edges would have been straight lines, and they are now indented curves. But perhaps that came from too many people handling them.

But I would not have described the foam as having resilience and able to rebound from compression.

One of the pour foams I tested was fairly brittle, I could take my thumb and when pressing into it, crunch it in and the indentation would remain with foam dust falling off. Similar to crafting foam which sheds dust when rubbed.

The foam I removed from my hull - I could deform the foam slightly before it'd "give", and you wouldn't hear much cracking, just be left with an indentation. I could still pop chunks of it out, it wasn't spongy at all, but there is definitely far more "spring" to the foam within the boat. Much better performance and along the lines of structural foam (I know - shocking as its used in a structural application!)

[jimh]

By the way, if Bob Dougherty were still alive, still at Boston Whaler as chief designer, and able to read this thread, he would probably contact you about a job at Boston Whaler in the prototype fabrication shop.

When Brunswick took over Boston Whaler, in the subsequent catalogues they would often tout the use of a multi-axis computer controlled cutting machine that was used to make the plugs that would form the molds for hull and liner parts. That is compared to the first hull molds which were taken off prototype hulls that has been refined in actual sea trials.

[Jpopsbronco]

I appreciate that. I'm a development engineer by day, I create specialty equipment used in the delivery space, not very experienced in fiberglass/gelcoat but it's fun to learn. It'd be fun to do new product development work in the marine space.

Couple more updates. I'm adding a removeable 13 gallon bait tank so I repurposed the thru hull (aka garboard thru hull as the whaler manual refers to it) to be the pickup for this tank, as well as the drain for the tank at the end of the day. For anyone wondering, at least on my 2018 130SS, the garboard thru hull plug internal thread fits 3/4 npt fittings. Pics to come of this setup.

I also disliked how the factory boarding ladder was just screwed to the transom. When I removed the screws, electrolysis had eroded the threads off the fasteners which had been living underwater. I did not see any evidence of sealant on the screws... So I removed the ladder, filled those holes and am building a proper swim step on each side of the motor. I need to do a bit more fab on the swim steps before they are strong enough to support a grown man "jumping" off of them, but I'll share the images of this too to see what others think.