Yep. It takes about 10-15 seconds, and I have to sit forward (I am 160lbs) at first and can't move back while planing. But when it gets on step it really hauls butt - that is until this "ventilation" problem happens.
Cavitating Tohatsu 3.5hp 4-stroke on Zodiac Zoom Air
- Thread starter patrickkidd
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- cavitation outboard
So this is already a 20" shaft which is pretty long, and as shown in the photos the transom already has a 2" dip in it to get the prop lower in the water. Do any of you have any experience with planing fins? A friend just suggested trying them.
I have a doelfin hydrofoil on my 9.8 Tohatsu and love it. It planes much more easily and stays on plane at slower speeds. Also the bow doesn't pitch up much prior to getting on plane so I can see over it at all times. But I think your cavitation plate may be too small for any commercially produced hydrofoils. I think there are some plans online to diy tho...
Yeah, that's what I'm figuring out, that none of the hydrofoil sets are really made for smaller engines.
I put a whale tail type fin on my 6 HP Tohatsu and ended my cavitation problems and it's easy to get the 9 ft inflatable up on a plane and keep it there at lower throttle settings. Mind you we don't use it that way very much but when we do its FUN FUN FUN.....
I have a 10' zodiac w/ 3.5 Johnson. This past summer mine started to do what I thought was a ventilation problem and it grew worse over time.
But it didn't make sense... I found the plastic prop had spun the hub -shear pin was fine. Replaced the hub and prop - problem solved.
- sure sounded like ventilation issue...
But it didn't make sense... I found the plastic prop had spun the hub -shear pin was fine. Replaced the hub and prop - problem solved.
- sure sounded like ventilation issue...
Well, I eventually found that making sure that the keel and floor are fully inflated has a major impact on the ventilation problem with this engine. I just used it this past weekend on a few different kinds of water conditions and it didn't ventilate once.
Thanks for all the tips. What a subtle and interesting topic...
Thanks for all the tips. What a subtle and interesting topic...
It's just a power issue. My guess is your're a pretty bug guy, and the 3.5 just isn't enough to get you on a plane. The prop is deep enough.
I'm curious to know your thinking for this. I am currently 155lbs. The boat gets on step after about 10 seconds and stays that way so long as the floor and keel are fully inflated. When the floor and keel were not fully inflated the boat would get on step after 10 seconds and then suddenly slow and stay slow with the prop spinning at high speed.
I have an over 30 year-old 4 hp, 2 cycle Mercury (actually a Yamaha with Mercury labels). It's not a long shaft, I bought for a prior Avon and have had it for a bigger airfloor model for the last 19 years.
I think that I'd not cut the transom down right away, I'd play with i) where you are sitting and loading the dingy; ii) the angle of the engine; and, iii) the pitch of the prop first.
When you say "step on", Patrick, do you mean give the engine more gas, or ???
A 3.5 HP should plane with one person on board in flat water -- maybe an adult and modest sized child or load in the dingy. However, you may be expecting too much from that little engine. It's advantage is its weight, fuel efficiency (if you don't go flat-out), and simplicity. It's really not a 9 or 10 HP that will "fly". But then taking the motor on and off the stern pulpits, how can anybody not like a small 2 cycle vs. a 4 cycle?
I think that I'd not cut the transom down right away, I'd play with i) where you are sitting and loading the dingy; ii) the angle of the engine; and, iii) the pitch of the prop first.
When you say "step on", Patrick, do you mean give the engine more gas, or ???
A 3.5 HP should plane with one person on board in flat water -- maybe an adult and modest sized child or load in the dingy. However, you may be expecting too much from that little engine. It's advantage is its weight, fuel efficiency (if you don't go flat-out), and simplicity. It's really not a 9 or 10 HP that will "fly". But then taking the motor on and off the stern pulpits, how can anybody not like a small 2 cycle vs. a 4 cycle?