Yes, another newbie ;)

[Steveclv]

I recently acquired my first pontoon - a 1980 24' Kayot, canvas sides and a 1979 Evinrude 85 V4 motor. Cleaned her up, replaced furniture, added 2 new batteries, solar panel and replaced the old bimini fabric and added a new second bimini on the front. It has the aluminum skins below the floor.

The engine was cavitating very badly when I tried her before the refit so I added a hydrodynamic 'hydrofoil' plate onto the cavitation plate and replaced the badly damaged aluminum prop with a 4 blade Conprop 13 1/2 X 15 (the aluminum was 3 blade, 13 3/4 X 15).

Launched her today and the engine pulls strongly but seems to top out at 4500 rpm (the plate says that working rpms are 4500-5500) but there is still some cavitation at max speed (which is about 15mph at a guess). Given the age of the engine, I'm happy for it to run at 4500rpm

I noticed that the toons sit fairly low in the water (they are dry inside) and when under way they cut through the water rather than lifting above it - is that normal?

I'm used to fiberglass boats where the water at the back of the boat is smooth but the water at the back of the pontoon seems very chaotic at speed - again is this normal? I tried to find a video of a pontoon underway on Youtube but couldn't find one so that I could compare mine to it.

The engine is obviously original based on dates and so I assume it's the correct length etc but any thoughts on cavitation causes and solutions?

One final question, she's docked in the marina (freshwater) but do I leave her with the engine down or up and resting on the towing safety bar?

Thanks all!

[HandymanHerb]

First Welcome, do you have any pictures of it sitting in the water or just pictures of the water line on the toons and engine, this would help us help you.

Post pictures at 640x480

I recently acquired my first pontoon - a 1980 24' Kayot, canvas sides and a 1979 Evinrude 85 V4 motor. Cleaned her up, replaced furniture, added 2 new batteries, solar panel and replaced the old bimini fabric and added a new second bimini on the front. It has the aluminum skins below the floor.

The engine was cavitating very badly when I tried her before the refit so I added a hydrodynamic 'hydrofoil' plate onto the cavitation plate and replaced the badly damaged aluminum prop with a 4 blade Conprop 13 1/2 X 15 (the aluminum was 3 blade, 13 3/4 X 15).

Launched her today and the engine pulls strongly but seems to top out at 4500 rpm (the plate says that working rpms are 4500-5500) but there is still some cavitation at max speed (which is about 15mph at a guess). Given the age of the engine, I'm happy for it to run at 4500rpm

You need to go down in pitch, one inch down give you 200 RPM up

I noticed that the toons sit fairly low in the water (they are dry inside) and when under way they cut through the water rather than lifting above it - is that normal?

Pontoon are displacement hulls made to cut through the water not ride on top

I'm used to fiberglass boats where the water at the back of the boat is smooth but the water at the back of the pontoon seems very chaotic at speed - again is this normal? I tried to find a video of a pontoon underway on Youtube but couldn't find one so that I could compare mine to it.

Here's a shot from a toon pulling a tube


The engine is obviously original based on dates and so I assume it's the correct length etc but any thoughts on cavitation causes and solutions?

We need to know how deep it is in the water

One final question, she's docked in the marina (freshwater) but do I leave her with the engine down or up and resting on the towing safety bar?

Leave it up you don't need stuff growing on your engine

Thanks all!

The rest of the guys will jump in soon to help too.

[Steveclv]

I'll take some measurements of the engine and also some video - the waterline is almost exactly half way up the tubes.

I'll try a less pitchy prop - those conprops are only $80 apiece and I could do with a spare one anyway.

Thanks for the vid - the water seems pretty turbulent there too rather than a defined wake that I'm used to but I'll show you the video if I get out on the lake tomorrow.

[dbltrblpapa]

Hey Steveclv,

Congratulations on the new toon. Here's a pic off the back of my boat from a few weeks ago if it helps.