Need prop help 1990 boston whaler 25 walkaround

[madman2021]

So I just bought this 1990 boston whaler 25 walkaround wide body with whaler drive(actually have 2 of them now)Has twin 1997 yamaha 225 ox66 that run perfect. They have 4 blade 14x19p props on it. Top speed was 37 mph with a dirty bottom at 5100 rpms. Lots of cavitation with these props. Can't trim up because of cavitation. Cavitates when trying to plane too. Previous owner said he bought it new and only used it to putt up and down the river with his grandchildren. Never ran it over 25 mph. I can believe that cause the boat was setup for low speed cruising sort of. Trim tabs stuck in full down position, and huge whale tails bolted to the lower units. Was able to get the trim tabs up and removed whale tails before test.

There was a boat test article back in 1989 for this exact boat. But they were running 200hp yamahas said the boat easily broke the 50 knot barrier. That's basically my goal.

 

[Bondo]

Re: Need prop help 1990 boston whaler 25 walkaround

So I just bought this 1990 boston whaler 25 walkaround wide body with whaler drive(actually have 2 of them now)Has twin 1997 yamaha 225 ox66 that run perfect. They have 4 blade 14x19p props on it. Top speed was 37 mph with a dirty bottom at 5100 rpms. Lots of cavitation with these props. Can't trim up because of cavitation. Cavitates when trying to plane too. Previous owner said he bought it new and only used it to putt up and down the river with his grandchildren. Never ran it over 25 mph. I can believe that cause the boat was setup for low speed cruising sort of. Trim tabs stuck in full down position, and huge whale tails bolted to the lower units. Was able to get the trim tabs up and removed whale tails before test.

There was a boat test article back in 1989 for this exact boat. But they were running 200hp yamahas said the boat easily broke the 50 knot barrier. That's basically my goal.

Ayuh,.... Until ya run some tests with a CLEAN hull, 'n runnin' gear, there ain't much to say,....

 

[madman2021]

Re: Need prop help 1990 boston whaler 25 walkaround

Freshwater dirty bottom. Just a thin slimmy green alge. No barnicales or heavey build up

 

[dazk14]

Re: Need prop help 1990 boston whaler 25 walkaround

Besides Bondo's suggestion.

Sometimes the best answer is no answer...

Jump over to the Boston Whaler Cult forums. There are a few. continuous wave, whaler Central, hull truth may have some and I'm probably forgetting one.

They'll have every combo under the sun.

edit: have you ever run this boat without slime? It can definitely lower performance significantly and promote ventilation. It may seem slippery, but it's not fast.

 

[madman2021]

Re: Need prop help 1990 boston whaler 25 walkaround

Ran the boat today with a clean bottom. Only got 38 mph out of her. Still have terrible cavitation.

 

[Bondo]

Re: Need prop help 1990 boston whaler 25 walkaround

So I just bought this 1990 boston whaler 25 walkaround wide body with whaler drive(actually have 2 of them now)Has twin 1997 yamaha 225 ox66 that run perfect. They have 4 blade 14x19p props on it. Top speed was 37 mph with a dirty bottom at 5100 rpms. Lots of cavitation with these props. Can't trim up because of cavitation. Cavitates when trying to plane too. Previous owner said he bought it new and only used it to putt up and down the river with his grandchildren. Never ran it over 25 mph. I can believe that cause the boat was setup for low speed cruising sort of. Trim tabs stuck in full down position, and huge whale tails bolted to the lower units. Was able to get the trim tabs up and removed whale tails before test.

There was a boat test article back in 1989 for this exact boat. But they were running 200hp yamahas said the boat easily broke the 50 knot barrier. That's basically my goal.

Ayuh,.... What's a Whaler Drive,..??

Where'd it, or they go,..??

What was put in it's place,..??

Is the last 4' to 6' of the bottom of the hull, Straight, 'n True,..??

 

[madman2021]

Re: Need prop help 1990 boston whaler 25 walkaround

Whaler drive is boston whalers house built outboard platform for closed transom boats. Just like a Armstrong bracket but fiberglass and it conforms to the hull. Here is a picture of the actual boat when I picked her up.