Longshaft engine

[xaden171]

Hi guys,
Would be great to hear your opinion and maybe put my mind at ease or help me with how to solve this situation.
I have a Honwave Ti38 vfloor and I just purchased a Yamaha 2 stroke 15HP longshaft, an upgrade of a Yamaha 5hp. Was wondering if it will be okay to use the 15HP with the boat. I know its not ideal but will it work without major issues?
Thanks for the help,
Bogdan

[Fenlander]

Hello and welcome to the forum.

I’d be very tempted to sell this outboard on and buy one of the correct short dimension. The long shaft will cause drag, possible splashing, upset the trim making it ride bow light, be more likely to allow the prop to be damaged etc.

[xaden171]

Thank you for the advice.
Unfortunately is a bit of a pain to find a short shaft for this HP, been looking for months for a decent one.
Managed to get this one for a good deal, hopefully it wasnt a rash decision purchase… I haven't tried yet on the boat. Will see how it goes and will let know.
Was even thinking of raising the transom on the honwave a bit by using a couple stainless steel plates if it is really bad without. I guess is some compromise.

[Fenlander]

I fully appreciate the situation with pricing and supply of 2-stroke 15hp motors in short shaft.

Of course yes give it a go, it may be satisfactory for your use and expectations.

Yes you can bring the transom up a bit with a timber section sandwiched between something like alloy plates. A full rise to put the prop where it should be will be mechanically unsatisfactory and put the outboard in a bit of a top heavy situation. Perhaps a halfway compromise?

Having said all that going through the pain of changing to the correct outboard will give a far better result with a far better feel to the outfit.

[Steve509926]

Originally Posted by Fenlander

Hello and welcome to the forum.

I’d be very tempted to sell this outboard on and buy one of the correct short dimension. The long shaft will cause drag, possible splashing, upset the trim making it ride bow light, be more likely to allow the prop to be damaged etc.

Agree with everything that Fenlander has mentioned plus I think you will struggle to maintain the sib on the plane.

As for extending the transom, take a look at this thread:-

https://www.rib.net/forum/f50/transom-extension-and-less-stress-possible-87202.html

[69cmw]

Originally Posted by xaden171

Hi guys,
Would be great to hear your opinion and maybe put my mind at ease or help me with how to solve this situation.
I have a Honwave Ti38 vfloor and I just purchased a Yamaha 2 stroke 15HP longshaft, an upgrade of a Yamaha 5hp. Was wondering if it will be okay to use the 15HP with the boat. I know its not ideal but will it work without major issues?
Thanks for the help,
Bogdan

I had a T38 and wouldn't even think about using a longshaft on it.
Getting a decent short shaft isn't that bad, just keep looking.

[Fenlander]

>>> wouldn't even think about using a longshaft on it.

I know. I hate to undermine the pleasure of a member, and a new one in particular, having the excitement of going from 5hp to 15hp but this long shaft will just not make the best of the power jump.

[jonp]

I put an extra long shaft on one of my boats rather than a long shaft using transom height brackets. Works great and has several advantages over using the intended size outboard. The cowling (powerhead) sits higher from the water eliminating spray or water from hard reversing to get into the intakes.

I don't know the boat you have or how well the transom is built.

Not sure if there are smaller ones available for sale but you could always get something made. This is the ones I have which can support up to 250hp https://www.ebay.com.au/itm/30513860...N9e8I57nptF3UM

[beamishken]

I fitted an extra long shaft engine to a longshaft transom as a temporary measure, expected it to be awful but it was surprisingly better than expected a bit of extra spray & probably a couple of kts slower than it should have been but useable all the same.
Only way to find out is try it, you've nothing to loose & might be happy for your purpose

[Davie]

Get a bit stainless sheet folded to make the boat a longshaft. You just have to take a little more care when rolling up. Alan from Fort Bill knows where to go to for this.

[xaden171]

Decided to test the engine a week later, I was very happy with it but as people pointed out the longshaft version created a few issues.
1- a waterfall going in the boat through the transom ( managed to half sort it by adjusting the tilt of the engine)
2 - Even though it was a lot faster then the 5hp ( was expected either way) I couldn’t go over 75% throttle due to raising water over the transom.

Sooo, I decided to raise the transom by 5inches on the Honwave Ti38 by using two stainless steel sheets and some 30mm thickness hard plastic. Going to try it out this weekend to see how it behaves, and hopefully not lose the engine lol

Here are some photos of the final piece, still want to weld the two sheets together at the top but need to ask a friend to do it for me.

[ATTACH][ATTACH][ATTACH][ATTACH][/ATTACH][/ATTACH][/ATTACH][/ATTACH]

[Steve509926]

I'd be tempted to put a couple more bolts through the plates and transom.
Good luck over the weekend

[Davie]

Drill more holes in the plate up and down for fine cavitation plate adjustment. Top job!