Shaft length for a 1995 26.8 Islander

[Timsjag]

Hi All, I picked up a 1995 Islander last year with a 225 Merc 4 stroke. The motor has a 30" shaft. Does anyone know whether this is the correct length? The boat has difficulty getting up on plane hence performance is rather poor (25 mph at 5800 rpm). I hate running a motor at full throttle all the time. When I put a straight edge from the keel to the cavitation plate it is about 2" above a straight edge. However if you measure from the bottom of the transom the cavitation plate is almost 10" below. The keel is about 28" forward of the transom. When I google how to determine the length of the motor everything says measure from the of the transom. I've gotten conflicting information from other chat line sites. Hopefully someone can give me the correct answer.

Tom

 

[ocnslr]

Congrats on your GW.

Now that you own one, I recommend you get familiar with their web site, and available support.

On the web site I was able to access the catalog for the 1995 models and confirmed what I was fairly sure of. Shaft length of 30” for single engine, 25” for twins, and max hp of 400.

Our 2002 Islander 270 originally had a single 250hp OX66, and we had friends with the same engine on an Islander 268. In both cases the power was just adequate, and those were strong 2-cycle 250hp engines.

While your stated performance indicates that you may have a problem with engine height, or prop size/design, I think you are trying to push a very heavy boat that is underpowered a lot. And that’s assuming your boat hasn’t “gained weight” over the years, or has a fouled bottom.

Can’t address prop slip without more information.

 

[Timsjag]

Thanks for your reply, I'm still trying to learn the site and it's support. After more research on other sites I've gotten the same answer. Right shaft length but under power. I'll be in the market for a used 300 hp, that should solve the power problem.

Again Thanks...

 

[ocnslr]

You’re quite welcome. A good 300hp single would be a major improvement.

And, based on personal experience, I strongly recommend a good four-blade prop that gets the correct WOT RPM. The four-blade will have a lot more bite. We ran a PowerTech OFS4 x 17” on our big single.

Don’t hesitate to contact Customer Service at Grady White, or come here, with questions. And best wishes with your Islander.

 

[scott1949]

I have a 1996 Islander and repowered in 2011 with F300. Big difference in performance from the 250. Put the Saltwater series prop, 15 3/4", 15 pitch prop. That is the ticket for my boat.