Pontoon Boat & Deck Boat Forum

So I recently picked up a 2001 StarCraft Starfish 20ft w/ an 1997 Johnson 90 (rated for 75). It’s underskinned and is really light on furniture, it only has one couch and the captains chair, trolling motor and the 2 accompanying batteries. Well once me and the wife got it out no matter what I could do the mph I could muster was about 21(on gps) @5500 RPM. The speed isn’t necessary a problem but I think it was a symptom of the outboard possibly being too low. While underway no matter how I trimmed the motor the transom deck area was soaked lots of splashing really at any speed. The motor is mounted on the lowest position.
Once we got it out the water I noticed a little sloshing in the tubes so it’s currently at the shop getting taken care of properly. But it didn’t seem like there was too much in there.
So let me know what you guys think, these are the pictures I took while cleaning it up and since it’s at the shop I can’t get any more at the moment.
So should I raise it up a couple spots or leave it as it’s?

Thank you for any help y’all can offer

Generally, from what I've read and seen your motor may be too HIGH. Typically, most of the time the correct config is when the cavitation plate on the motor is about even with the bottom of the toons. Yours seems to be a bit higher than that. It seems like most of the older pontoons like yours that I see do throw up a lot of water around the transom, especially when the engine mounts in that recessed area of the transom, But 21 mph on a pontoon with that size engine is pretty good. Remember, you've got a displacement hull that is really just being pushed through the water, rather than being on top of it.

steve1313 wrote: ↑

Mon May 23, 2022 5:35 am

Generally, from what I've read and seen your motor may be too HIGH. Typically, most of the time the correct config is when the cavitation plate on the motor is about even with the bottom of the toons. Yours seems to be a bit higher than that. It seems like most of the older pontoons like yours that I see do throw up a lot of water around the transom, especially when the engine mounts in that recessed area of the transom, But 21 mph on a pontoon with that size engine is pretty good. Remember, you've got a displacement hull that is really just being pushed through the water, rather than being on top of it.

Really? I have done some research, although this is a difficult topic to find. I seen something saying the cavitation plate actually should be in the 2-3 inch range below the transom not the 9-10 inches it currently has. Maybe someone else can clear up the confusion.

On the twins toon boats around here we set the cavitation plate even with the botton of the transom or an inch or two lower. It also depends on the transom shape. I would try moving up a notch at a time until it cativates and then move it down one notch. Check for cacitation when turning and when you have your normal load of people and gear.

Stimpy wrote: ↑

Mon May 23, 2022 7:57 am

Really? I have done some research, although this is a difficult topic to find. I seen something saying the cavitation plate actually should be in the 2-3 inch range below the transom not the 9-10 inches it currently has. Maybe someone else can clear up the confusion.

OK, my bad. The advice I gave you is more applicable to a tritoon, not a two log toon. Sorry, I have a tritoon and my brain just assumes that's what every boat is.

rbtnt wrote: ↑

Mon May 23, 2022 8:02 pm

On the twins toon boats around here we set the cavitation plate even with the botton of the transom or an inch or two lower. It also depends on the transom shape. I would try moving up a notch at a time until it cativates and then move it down one notch. Check for cacitation when turning and when you have your normal load of people and gear.

Yeah that’s what I was thinking I’ll give it a shot.

steve1313 wrote: ↑

Tue May 24, 2022 2:18 am

Stimpy wrote: ↑

Mon May 23, 2022 7:57 am

Really? I have done some research, although this is a difficult topic to find. I seen something saying the cavitation plate actually should be in the 2-3 inch range below the transom not the 9-10 inches it currently has. Maybe someone else can clear up the confusion.

OK, my bad. The advice I gave you is more applicable to a tritoon, not a two log toon. Sorry, I have a tritoon and my brain just assumes that's what every boat is.

No worries! Thank you for your reply