Q1: what engine should be used to re-power [a c.1970 SPORT 13]?
BACKSTORY
I may use a new Mercury 30-HP or 40-HP engine to re-power a c.1970 SPORT 13.
The weight of the Mercury 30-HP engine is close to the weight of the Yamaha two-stroke-power-cycle 30-HP engine now on the c.1970 SPORT 13.
I will use the c.1970 SPORT 13 on a chain of lakes. There are Mercury and Yamaha engine dealers there, so buying a new Mercury or Yamaha outboard engine will make service for the new engine convenient for me. There are other brands [of 30-HP engines] available.
1974 SPORT Re-power with Short Shaft or Long Shaft Engine
Re: c.1970 SPORT 13
When re-powering a 50-year-old Boston Whaler boat, keeping the engine weight as light as possible is a good consideration.
To help readers understand the engine weights involved in this decision, you should provide the engine weights of the five engines you mention:
Another consideration when re-powering is the possible benefit of staying with the same brand on the possibility of being able to reuse some of the engine rigging components such as fuel hoses, fuel connectors, steering links, ignition key switch, warning alarms, and engine gauges. On the other hand, if all the engine rigging is also 50-years old, the best choice is probably to abandon all the old electrical and fuel rigging. The old fuel rigging, in particular, can be a huge risk to a new engine. Any flow restriction in the fuel system can cause engine damage that will not be covered under warranty.
Accounting for post-sale service for a new engine is also an important factor. Even new engines will need some service, particularly during the warranty coverage interval.
In today’s boating business almost all new engines are sold pre-rigged on new bosts by the boat builder. Not all dealers representing a particular engine brand will have experience with selling and installing a “loose” new engine. Visit local engine dealers and ask about how many loose new engines they sell and install on 50-year-old boats.
To help readers understand the engine weights involved in this decision, you should provide the engine weights of the five engines you mention:
- existing engine
- Mercury 30-HP
- Mercury 40-HP
- Yamaha 30-HP
- Yamaha 40-HP
Another consideration when re-powering is the possible benefit of staying with the same brand on the possibility of being able to reuse some of the engine rigging components such as fuel hoses, fuel connectors, steering links, ignition key switch, warning alarms, and engine gauges. On the other hand, if all the engine rigging is also 50-years old, the best choice is probably to abandon all the old electrical and fuel rigging. The old fuel rigging, in particular, can be a huge risk to a new engine. Any flow restriction in the fuel system can cause engine damage that will not be covered under warranty.
Accounting for post-sale service for a new engine is also an important factor. Even new engines will need some service, particularly during the warranty coverage interval.
In today’s boating business almost all new engines are sold pre-rigged on new bosts by the boat builder. Not all dealers representing a particular engine brand will have experience with selling and installing a “loose” new engine. Visit local engine dealers and ask about how many loose new engines they sell and install on 50-year-old boats.
1974 SPORT Re-power with Short Shaft or Long Shaft Engine
Q1: should I re-power my 1974 SPORT [unspecified length] with a short-shaft engine, or with a 20-inch shaft engine combined with an KOSKIP transom mount?
Q2: among short shaft engines from Mercury and Tohatsu of 25 or 30-HP, or 20-inch-shaft engines from Suzuki, Tohatsu, or Mercury of 30-HP (and mounting them with a KOSKIP transom mount or building up the transom) which should be used for the re-power?
The Suzuki, Tohatsu, or Mercury 30-HP engines all weight about 150-lbs, which is the same weight an old Yamaha 30-HP two-stroke-power-cycle engine [possibly the engine in use on 1974 SPORT [unidentified length].
Q2: among short shaft engines from Mercury and Tohatsu of 25 or 30-HP, or 20-inch-shaft engines from Suzuki, Tohatsu, or Mercury of 30-HP (and mounting them with a KOSKIP transom mount or building up the transom) which should be used for the re-power?
The Suzuki, Tohatsu, or Mercury 30-HP engines all weight about 150-lbs, which is the same weight an old Yamaha 30-HP two-stroke-power-cycle engine [possibly the engine in use on 1974 SPORT [unidentified length].
Re: 1974 SPORT Re-power with Short Shaft or Long Shaft Engine
Q3: what is the length of the 1974 SPORT?
Q4: what is a KOSKIP mount?
Q5: what method of steering the engine will be used in the re-power?
I am not familiar with a KOSKIP outboard engine mount, and a search for information was not productive.
Q4: what is a KOSKIP mount?
Q5: what method of steering the engine will be used in the re-power?
I am not familiar with a KOSKIP outboard engine mount, and a search for information was not productive.
Re: 1974 SPORT Re-power with Short Shaft or Long Shaft Engine
If you have an old Boston Whaler requiring a 15-inch or short shaft engine, then I think you must have a pre-1972 13 footer. If so then my experiences with my 1971 Sourpuss 13 might be relevant.
When I bought the 1971 Sourpuss 13 boat back in the [1990's], it came with a 1978 Johnson 35-HP engine a 20-inch-shaft shaft. I was young, stupid, and oblivious to the fact that the outboard shaft length was wrong. The motor actually performed very well with little or no backsplash. We used that configuration, usually with two adults, two kids, a black labrador retriever, and a day's supply of food and gasoline on board. The Johnson 35 weight was about 120-lbs, and the lower unit was quite slight. I believe this was a viable and common re-power option back in that era.
When the lower unit went out on the Johnson, I went to my local Mercury dealer. I wanted power trim and tilt but that was not an option for a short shaft in 2001. The dealer installed a 30-HP four-stroke-power-cycle engine with 20-inch shaft and power trim, using a jack plate to raise the engine as well as setting it back 6-inches. What a disaster! The boat was so stern heavy I didn't dare leave it tied to the dock overnight. One financial bath later, the engine and jack plate were returned to the dealer.
Then I re-powered for the second time with a 2001 Yamaha 25-HP four-stroke-power-cycle engine with a short shaft. Wonderful!
The lack of power trim was not a problem. I did miss the vintage look of the old Johnson, but the Yamaha had very adequate power (although we now had a bigger boat for water sport). The improvement in fuel economy and lack of fussiness was out of this world.
Around 2012 the 1971 Sourpuss 13 boat was stolen off its mooring. I found it the next day on the other side of the lake missing the Yamaha engine. I fully restored the boat and this time bought a cosmetically refreshed 1990 Johnson 40-HP short shaft off Craigslis--re-power number three. Maybe that was an over reaction to not wanting another motor stolen.
Now the boat looks absolutely fantastic. But I am still unhappy. My beef is that, without PTT, there is no place to put the tilt pin that works well for all power ranges. Where I am at now the boat performs great until I try to exploit the 40-HP. As power goes up you can just feel the bow plow. Because the boat is now used mostly by younger house guests I've decided that is a better option than a porpoising rocket ship. Also, it is back to being a fussy, smelly, noisy fuel hog.
If I am reading my Google search engine correctly, Yamaha now makes a 25-HP four stroke short shaft with PTT that weighs under 130-lbs. I wish that had been an option in 2001. And it can be ordered in white--perfect!
Re-power number four...
When I bought the 1971 Sourpuss 13 boat back in the [1990's], it came with a 1978 Johnson 35-HP engine a 20-inch-shaft shaft. I was young, stupid, and oblivious to the fact that the outboard shaft length was wrong. The motor actually performed very well with little or no backsplash. We used that configuration, usually with two adults, two kids, a black labrador retriever, and a day's supply of food and gasoline on board. The Johnson 35 weight was about 120-lbs, and the lower unit was quite slight. I believe this was a viable and common re-power option back in that era.
When the lower unit went out on the Johnson, I went to my local Mercury dealer. I wanted power trim and tilt but that was not an option for a short shaft in 2001. The dealer installed a 30-HP four-stroke-power-cycle engine with 20-inch shaft and power trim, using a jack plate to raise the engine as well as setting it back 6-inches. What a disaster! The boat was so stern heavy I didn't dare leave it tied to the dock overnight. One financial bath later, the engine and jack plate were returned to the dealer.
Then I re-powered for the second time with a 2001 Yamaha 25-HP four-stroke-power-cycle engine with a short shaft. Wonderful!
The lack of power trim was not a problem. I did miss the vintage look of the old Johnson, but the Yamaha had very adequate power (although we now had a bigger boat for water sport). The improvement in fuel economy and lack of fussiness was out of this world.
Around 2012 the 1971 Sourpuss 13 boat was stolen off its mooring. I found it the next day on the other side of the lake missing the Yamaha engine. I fully restored the boat and this time bought a cosmetically refreshed 1990 Johnson 40-HP short shaft off Craigslis--re-power number three. Maybe that was an over reaction to not wanting another motor stolen.
Now the boat looks absolutely fantastic. But I am still unhappy. My beef is that, without PTT, there is no place to put the tilt pin that works well for all power ranges. Where I am at now the boat performs great until I try to exploit the 40-HP. As power goes up you can just feel the bow plow. Because the boat is now used mostly by younger house guests I've decided that is a better option than a porpoising rocket ship. Also, it is back to being a fussy, smelly, noisy fuel hog.
If I am reading my Google search engine correctly, Yamaha now makes a 25-HP four stroke short shaft with PTT that weighs under 130-lbs. I wish that had been an option in 2001. And it can be ordered in white--perfect!
Re-power number four...
Re: 1974 SPORT Re-power with Short Shaft or Long Shaft Engine
That's why the OP needs to be clear about the boat length. If he thinks he has a 1974 13-footer, I would be surprised if the transom was intended for a 15-inch-shaft engine, unless perhaps some prior owner took a saw to it.kladd wrote:If you have an old Boston Whaler requiring a 15-inch or short shaft engine, then I think you must have a pre-1972 13 footer.
ASIDE
KLADD--I enjoyed your narrative about the SOURPUSS 13. If my recall is correct, my wife's aunt used to have a really old 13-footer non-smirk hull with a 25-HP two-stroke-power-cycle engine. That boat and engine could actually be used for water skiing, as long as the water skier was quite slim and was getting up on two skis.
Re: 1974 SPORT Re-power with Short Shaft or Long Shaft Engine
ASIDE: Jim, you make a great point and I totally agree that a 25-HP-powered 13-footer is perfectly adequate for lightweight water skiers.
One of my first childhood memories boating is my grandfather getting my father up on skis with a fiberglass boat powered by a Scott-Atwater 43.7-HP engine. Maybe not pretty but 6-foot-5-inch-tall Dad did get up on two skis. There, I just dated myself!
One of my first childhood memories boating is my grandfather getting my father up on skis with a fiberglass boat powered by a Scott-Atwater 43.7-HP engine. Maybe not pretty but 6-foot-5-inch-tall Dad did get up on two skis. There, I just dated myself!
Re: 1974 SPORT Re-power with Short Shaft or Long Shaft Engine
{Moderator's note: merged two threads started by same OP on similar topics.]