CONTINUOUSWAVE

The brass drain tubes used by Boston Whaler in the 1980's may have been economical for the factory and acceptable in the early years of the Boston Whaler boat production, but brass tubes as drain tubes have been found by some to be a major culprit leading to water intrusion into the foam core of Unibond hulls. Perhaps one could argue if the brass tubes were maintained properly they wouldn't leak. However the continual maintenance of a brass drain tube can be eliminated if the brass tube is replaced by a modern substitute material: fiberglass.

Fiberglass tubes are incredibly easy to install and unlike the original brass tubes they will never corrode. Best of all: you don't need to purchase flaring tools. And fiberglass tube is inexpensive

On my REVENGE 22 hull I have changed all of the brass drain tubes to be fiberglass tubes. I have also added several additional drains.

As a source of fiberglass tubes, I purchased them at Max Gain Systems. They make a 3/4-inch- ID tube with a 1-inch OD that will be very close to your original brass tube outside diameter. A 23" tube is $7.25:

https://mgs4u.com/product/1-od-round-tube/

In order to use the original brass tube drain plugs, you must use fiberglass tubes with a 1-inch-ID and a 1-1/4-inch OD. A 23" tube is $8.07:

https://mgs4u.com/product/1-14-od-round-tube/

In order to use the 1-1/4-inch OD fiberglass tubes, the original holes in the Unibond hull must be increased in side to be allow the 1-1/4-inch ID tube to pass through them. To increase the side of the holes I used an inexpensive 1-1/4-inch diameter drill on the wood transom core end of the hole. For the other end of the hole where the material is just fiberglass, an inexpensive sanding drum set from Harbor Freight on a drill works well:

https://www.harborfreight.com/sanding-d ... 60741.html

The fiberglass tube ends easily sand to the angle to match your hull angle so they fit flush.

The fiberglass tubes must be set in place with a strong adhesive. The marine epoxy sold under the Marine-Tex brand is easy to work with. The WEST Systems Six10 epoxy is a very strong adhesive and is also easy to use. See

https://www.westsystem.com/specialty-epoxies/six10-thickened-epoxy-adhesive/

What is the permeability to water intrusion of the fiberglass tubes?

The lower end of the drain tubes are typically always immersed in water. If a Unibond hull boat lives in water, is there a reasonable concern for the fiberglass tubes becoming saturated with water at their below-the-waterline end?

ASIDE. On my 1990 REVENGE 22 all of the brass drain tubes are original, and I do not have any evidence of corrosion in them, although on one of the drain tubes there seems to be a inward kink in the tube that reduces the ID slightly in one part.

jimh wrote:What is the permeability to water intrusion of the fiberglass tubes?

The lower end of the drain tubes are typically always immersed in water. If a Unibond hull boat lives in water, is there a reasonable concern for the fiberglass tubes becoming saturated with water at their below-the-waterline end?

Jim, your question about the permeability to water intrusion is a very good question.

I checked with Max-Gain Systems

Here is their answer:

Max-Gain Systems wrote:Our tubes are made with isophthalic polyester resin, and water absorption is quite low.

Our tubes are structural, and are NOT designed for liquid transport, and could leak water. We do not guarantee water-tightness.

If that is what you need, you might try Strongwell, who makes tubes for the petroleum industry. Some customers have used our tubes and have coated them internally or externally with materials or products such as POR-15 to achieve water-tightness.

OBVIOUSLY THE TUBES I RECOMMENDED ABOVE ARE NOT THE TUBES TO USE.

Better fiberglass tubes for this application are obviously out there to be found. Also, an easy solution would be Carbon Fiber tubes utilizing epoxy resin.

At the beginning of the restoration of my Revenge 22 I couldn't find fiberglass tubes so I made all of my drain tubes below deck myself using 1-inch OD and 1-1/4-inch OD conduit tube as a mandrel utilizing fiberglass sleeve and West Systems epoxy.
Here is a link to the sleeve materials that I used: https://www.fibreglast.com/product/Brai ... ed_Sleeves

Making the tubes was a real pain but I was intent on a waterproof replacement for the Brass tubes that could not corrode.
I do not recommend going through this hassle because it would be far easier to find fiberglass or carbon fiber tubes that will work as a good replacement.

Here is a quick google search on Carbon Fiber/Epoxy tubing that could work as a replacement:
https://store.acpcomposites.com/carbon- ... ensions=30

My first thought was this carbon fiber tubing is very expensive. Then I looked at the brass tube prices on McCaster Carr's website and found that brass has gone way up since I purchased it.

jimh wrote:What is the permeability to water intrusion of the fiberglass tubes?

ASIDE. On my 1990 REVENGE 22 all of the brass drain tubes are original, and I do not have any evidence of corrosion in them, although on one of the drain tubes there seems to be a inward kink in the tube that reduces the ID slightly in one part.

[Corrosion of brass drain tubes is not] much concern for [freshwater] boaters. I'd expect drain tubes [used in freshwater[ to outlast the ones used in saltwater.

I'm an ocean boater (with some lake use) and whenever I see an classic Boston Whaler boat in the boatyard, the first things I look at are the brass drain tubes. I have seen plenty brass drain tubes that are compromised, and the owner isn't even aware. Marinas seem to be ripe for corrosion with the saltwater and many dissimilar metals and electricity on the docks.

D-

Why not coat [the fiberglass replacement drain tubes] in epoxy prior to installation?

Vance's Revenge wrote:The brass drain tubes used by Boston Whaler in the 1980's may have been economical for the factory and acceptable in the early years of the Boston Whaler boat production, but brass tubes as drain tubes have been found by some to be a major culprit leading to water intrusion into the foam core of Unibond hulls. Perhaps one could argue if the brass tubes were maintained properly they wouldn't leak. However the continual maintenance of a brass drain tube can be eliminated if the brass tube is replaced by a modern substitute material: fiberglass.

Fiberglass tubes are incredibly easy to install and unlike the original brass tubes they will never corrode. Best of all: you don't need to purchase flaring tools. And fiberglass tube is inexpensive.

Great idea and I've thought of doing this, but never got around to it and the brass tube was an easy install. The fiberglass tubes I looked at were thinner wall and my concern was the plug and creating fractures if tightened too tight. It looks like the wall thickness of the tubes you posted is much better than the material I looked at. My other concern was bonding of the tube to the inner and outer skins since the contact point is so small and the slightest movement in material would cause a crack at the interface. My idea for overcoming that would be to "hog out" the area of foam where the tube would be placed and flood that area with epoxy to create an internal bond between the tube and the inside cavity of the inner and outer skins. This way, no matter how much abuse, movement or freezing of wet foam, there would be little to no chance the tube would ever move and compromise the watertight integrity.

D-

Max-Gain Systems wrote:Some customers have used our tubes and have coated them internally or externally with materials or products...to achieve water-tightness.

Phil T wrote:Why not coat [the fiberglass replacement drain tubes] in epoxy prior to installation?

I think MaxGain Systems and PHIL T are thinking similarly about improving the resistance to ingress of water into fiberglass tubes.

dtmackey wrote:....My idea ...would be to "hog out" the area of foam where the tube would be placed and flood that area with epoxy to create an internal bond between the tube and the inside cavity of the inner and outer skins. This way, no matter how much abuse, movement or freezing of wet foam, there would be little to no chance the tube would ever move and compromise the watertight integrity.

Mentioned earlier:

Vance's Revenge wrote:The brass drain tubes used by Boston Whaler in the 1980's may have been economical for the factory...

Here the economy was probably in the reduced labor time to install the brass tubes compared with the more elaborate techniques suggested for fiberglass replacement tubes. Another concern: the more permanent the installation of the a replacement tube is made, the more difficult future removal of the replacement tube will become.

Note that Boston Whaler has switched to non-brass drain tubes, but the plastic tubes they used have not be maintenance-free. Also, when those plastic drain tubes fail, Boston Whaler recommends the dealer be employed to replace them, perhaps an indicator of the degree of difficulty involved in the removal of the existing tube and its proper replacement.

On my Mako rehab 17 years ago, I removed the double brass tubes that the factory used and enlarged the deck drains and then made my own internal fiberglass tube by lining with fiberglass and then inflating a balloon to keep in place and remove the air bubbles from the resin. This was further glassed into place, but also had solid wood core around it instead of weak foam for support



I do like the fiberglass tube idea better than brass.

D-

dtmackey wrote:

Vance's Revenge wrote:The brass drain tubes used by Boston Whaler in the 1980's may have been economical for the factory and acceptable in the early years of the Boston Whaler boat production, but brass tubes as drain tubes have been found by some to be a major culprit leading to water intrusion into the foam core of Unibond hulls. Perhaps one could argue if the brass tubes were maintained properly they wouldn't leak. However the continual maintenance of a brass drain tube can be eliminated if the brass tube is replaced by a modern substitute material: fiberglass.

Fiberglass tubes are incredibly easy to install and unlike the original brass tubes they will never corrode. Best of all: you don't need to purchase flaring tools. And fiberglass tube is inexpensive.

Great idea and I've thought of doing this, but never got around to it and the brass tube was an easy install. The fiberglass tubes I looked at were thinner wall and my concern was the plug and creating fractures if tightened too tight. It looks like the wall thickness of the tubes you posted is much better than the material I looked at. My other concern was bonding of the tube to the inner and outer skins since the contact point is so small and the slightest movement in material would cause a crack at the interface. My idea for overcoming that would be to "hog out" the area of foam where the tube would be placed and flood that area with epoxy to create an internal bond between the tube and the inside cavity of the inner and outer skins. This way, no matter how much abuse, movement or freezing of wet foam, there would be little to no chance the tube would ever move and compromise the watertight integrity.

D-

I'm absolutely positive it is not necessary and I never mentioned this process because it probably could cause a fire. I actually did flood around the tube on the tubes in the floor drains on my 22 Revenge restoration.

I hogged out and compressed the foam with my finger larger than the tube, cleaned, prepped and coated the bottom hole and the bottom of the tube with Marine-Tex and inserted it in place holding it with masking tape. I set the tube slightly lower than the bottom of the boat to be sanded flush later. I then went inside and adjusted the tube holding it in place with masking tape at the top as well.
I let the epoxy set up so the tube was solid in place being held by the epoxy at the bottom.

On the top I had pre-drilled 4 holes around the tube at 90, 270, 0 and 180 degrees. I took a big syringe I purchased at Tap Plastics with a clear tube added to the syringe that would reach the bottom of the hull through the holes I drilled. I then injected West Systems Epoxy thickened with filler from the bottom up around the tubes. It turned out to be very scary and I'm by far no expert to rate this as dangerous, but I think it is dangerous! The epoxy gets incredibly hot and reacts with the foam. In some cases it foamed up and extruded out the holes at the top smoking. I liked the foam reaction because I felt it laminated the tubes into place with a thick solid epoxy/foam solution.
The worst one was at the very front tube in the bow section. It was smoking like mad and got incredibly hot. I kind of panicked for a few minutes worrying if it was going to ignite. I did this on cool mornings. It is incredibly scary and I don't recommend it without doing some research with the chemicals....I may have just got lucky by not having it ignite.

After everything cooled and finished setting up. I used a Dremel tool to clean around the top of the tube and holes and injected them with a syringe of Marine-Tex to seal the top sections. After years of pounding this boat in rough water. There are zero cracks around the tubes.

Also, I wouldn't worry about using thin tubes and cracking. If the tube is installed with Marine-Tex or thickened epoxy, the epoxy will reinforce the tube into the substrate behind the tube and prevent cracking.

There has to be fiberglass tubes available made with epoxy that would be less expensive than carbon fiber tubes. Fiberglass tubes should not be able to cause galvanic corrosion either.

Carbon Fiber tubes can cause galvanic corrosion if they contact metal. But I would think a rubber boat plug should never contact the tube and if the tube was sanded and coated with West Systems or another quality epoxy resin it will be completely insulated.

Here is a reply from ALLRED and Associates answering my questions about water intrusion and their carbon fiber tubes.

Sharon Jennings wrote:Vance--Thank you for your interest in our carbon fiber tubes. Your question was forwarded to our engineers and the following is their response:

Engineers wrote:Our Prepreg Carbon tubes are resistant to water absorption, the main problem would be galvanic corrosion between dissimilar materials (whatever material the carbon would be connected to). This is something we cannot comment on and would need to be tested by the customer for their application.

Here is a link to our Prepreg Carbon Fiber Tubes:

https://dragonplate.com/carbon-fiber-roll-wrapped-twill-tube-125-id-x-24-gloss-finish

They also have 1" ID tubes.


If you have further questions, feel free to reach out again.

Sharon Jennings
sjennings@allredcorp.com
http://www.allredcorp.com

Can fiberglass tubes be used as replacement drain tubes in saltwater with success?

LONG BACK STORY
I just received four feet of the [Max Gain Systems] one-inch-ID tube. I think roughing up the fiberglass tubes [and then applying a] few coats of WEST Systems epoxy would seal the tubes. If the [the fiberglass tubes sealed with epoxy] started letting water penetrate, then [the fiberglass tube diameter could be increased] and a brass tube could be installed into the fiberglass tube. The drain tubes [on my unidentified boat have] all been taken out. I do not want to be a Guinea pig. [On some unidentified boat]the drains have a 90-degree-fit on one end and some different fit on the other end. I do have a flaring tool. I don't want to mess up a bunch [of brass tubes] getting the right angle, nor do I want to worry about them leaking. I am not that experienced flaring the tubes.I did see something about bending the threaded rod with the dies but wondered if when tightening if the rod would flex back to straight and mess up the angle.

dave3825us wrote:Can fiberglass tubes be used as replacement drain tubes in saltwater with success?

Your question is answered in the third paragraph of the first post in this thread.

dave3825us wrote:Can fiberglass tubes be used as replacement drain tubes in saltwater with success?

LONG BACK STORY
I just received four feet of the [Max Gain Systems] one-inch-ID tube. I think roughing up the fiberglass tubes [and then applying a] few coats of WEST Systems epoxy would seal the tubes. If the [the fiberglass tubes sealed with epoxy] started letting water penetrate, then [the fiberglass tube diameter could be increased] and a brass tube could be installed into the fiberglass tube. The drain tubes [on my unidentified boat have] all been taken out. I do not want to be a Guinea pig. [On some unidentified boat]the drains have a 90-degree-fit on one end and some different fit on the other end. I do have a flaring tool. I don't want to mess up a bunch [of brass tubes] getting the right angle, nor do I want to worry about them leaking. I am not that experienced flaring the tubes.I did see something about bending the threaded rod with the dies but wondered if when tightening if the rod would flex back to straight and mess up the angle.

I think you are on the right track cleaning and roughing up the [Max Gain Systems] tubes and coating them with West System epoxy slightly thickened with Silica. If the fiberglass tube is insulated with a couple coats of epoxy, water cannot get to the tube. You will need to coat each end of the tubes with epoxy after you sand them off flush with the hull as well.

Adding a brass sleeve in the tube is unnecessary and could be a nightmare to remove down the road when it has corroded. If your going to add a sleeve PVC in the tube will be inexpensive and never corrode. But, again, I can't see a sleeve as necessary unless you are just adding a small 1-1/2 length as a sleeve to prevent the drain plug from wearing on the West Systems epoxy in the tube.

Regarding epoxy resin becoming hot while curing:

The chemical reaction that occurs when epoxy resin and hardener are mixed is an exothermic reaction. The rate of the curing reaction increases with temperature. If a large mass of epoxy resin is instilled into a void or space in the foam interior of a Unibond hull, as this large mass of epoxy begins to cure it emits heat. The heat raises the temperature of the epoxy resin and hardener. The rising temperature causes the chemical reaction to occur faster, releasing more heat at a faster pace. This is a classic closed-loop feedback system.

This property of chemical reactions to be exothermic and to release heat is well know. That epoxy resins exhibit this behavior is well known.

If using WEST System epoxy, read their epoxy application guide for advice. There are several ways to prevent a runaway reaction:

• begin the process of mixing and apply the resin and hardener at a lower ambient temperature; don't start the process with a 90-degree-F ambient temperature
• avoid application of epoxy resins in which a large volume of nothing but epoxy resin is created; the resin is not a filler, it is an adhesive; if you need to fill a void in the foam, introduce new foam
• use a slow-cure formulation of resin and hardener
• add low-density filler to the epoxy to increase the volume and avoid pure epoxy in a large mass

WEST System has advice against trying to thin epoxy resin to create better flow, and specifically mentions that the resistance to water can be compromised. See

https://www.epoxyworks.com/index.php/th ... tem-epoxy/

For coating the inside of fiberglass tubes, perhaps a foam applicator brush on a long rod or handle would be a suitable method to apply and evenly spread a thin coat of epoxy.

I have little faith in brass drain tubes. I am determined to find a better way to make replacement drains.

I ordered a length of 1-inch-ID, 1-1/4-inch OD tubing [of unmentioned material, presumed to be fiberglass] from Max Gain [Systems].

I found the following problems with the tubing:

• there are grooves on the inside surface of the tubing, almost like rifling in a gun barrel; a drain plug will not seal the tube no matter how tightly the plug is set.
• I slathered [TotalBoat] TotalFair fairing compound inside the ends of the tube then sanded smooth. The plugs now seal without a leak;
• there were two pinhole leaks in the tubing.

Max Gain makes it very clear that they make no claim of water tightness for there fiberglass tubing. It would seam the leaks are more probable than merely possible. The pinholes seem to coincide with the grooves on the tubes interior.

I believe these flaws can be addressed but not by a hack such as myself. I will continue the search for a suitable substitute for brass drain tubes.

Kingfish wrote:...I slathered [TotalBoat] TotalFair fairing compound inside the ends of the tube then sanded smooth.

What is the permeability to seawater of the TotalBoat TotalFair fairing compound?

I do not expect that a fairing compound would be completely impervious to continual immersion in water. The nature of a fairing compound is to be top coated--often with several layers--of other material which will be impervious to water--or a least much better at tolerating immersion in water than a fairing compound.