Outboard shaft length for inflatable

[tyce]

What length should the leg on my outboard be for my standard air floor inflatable. I always thought that inflatables were suited to a short shaft which is what I have but when I get up on the plane the prop cavitates and loses grip so I am guessing it should be a long shaft, what does everyone else have.

 

[lustyd]

I think it just needs to be lower than the hull, so if the fins are below that you should be fine. maybe wrong angle?

 

[VicS]

What length should the leg on my outboard be for my standard air floor inflatable. I always thought that inflatables were suited to a short shaft which is what I have but when I get up on the plane the prop cavitates and loses grip so I am guessing it should be a long shaft, what does everyone else have.

The anti-ventilation plate above the prop should be level with the bottom of the transom ( bottom of the dinghy, or a tiny bit lower, if it's a round-tail )

AFAIK small inflatables only require 15" shaft engines. A longshaft ( 20") would cause unnecessary drag

There is a similar question currently on the mobo forum, although that realates to a RIB not an air floor dinghy. Might be worth finding and reading

When you say air floor you do mean an inflated keel, presumably, not a simple flat inflated floor

 

[landlockedpirate]

Pretty much all inflatables take short shaft motors. You are having a normal problem associated with airfloor boats. When you get on the plane the floor starts to undulate, this messes up the water flow under the hull and causes the prop to cavitate.

All you can do is make sure the floor, tubes and keel (If it has one) are inflated to exactly the right pressure. You need to check the pressues after the boats been in the water for a bit and top up if needed. This is especially important if you have an inflatable V floor.

Sorry its not better news, its just one of the compromises you have to live with for the ease of use and lightweight of the airfloor.

 

[dingdongs]

you may have different holes to set the trim of the drive.Make sure its set on the one to be fully down.

 

[TQA]

A pair of Dolpin fins may help