Implications of shaft being too long?

[alt]

I have a small 3m inflatable tender that planes nicely with my 3.5HP short shaft. Problem is that it wont plane with 2 people in it.

So i've found a nice 6HP for it (boat can take upto 10HP) but it's a long shaft. Is there any drawbacks as to putting on a long shaft engine? Apart from it sitting in the water and more chance of hitting something... any safety or performance issues??

[Tim M]

For that size don't worry about it you should be fine. I had a 2.6m inflatable once that we used to put a 6hp longshaft Johnson on and it ran fine - would plane easily with 2 people. You might get a bit of spray if your unlucky but thats about it.

[prairie tuber]

Have you tried googling " Shaft too long for inflatable " ?

[alt]

Originally Posted by prairie tuber

Have you tried googling " Shaft too long for inflatable " ?

Nice

Tim - Thank's for the reassurance. I would prefer a short shaft (run in shallower water etc) but i've spotted a nice 6HP for sale, just wanted to make sure I wasn't going to be wasting my time.

[Derrick]

Alt

Have a look here http://www.ribs.co.uk/page/choose_motor

[alt]

Derrick - Thanks for that.

Will the wrong shaft length work on my boat ?

NO! Short shaft on a long transom may not even reach the water, water flow and cooling will be affected and performance will be dreadful. Long shaft on a short transom is dangerous. The point of thrust is way to low in the water and in the case of say 8 hp opening the throttle may flip a small boat over.

So I can try backflips? Woohoo!!!

[jyasaki]

Originally Posted by prairie tuber

Have you tried googling " Shaft too long for inflatable " ?

That sounds like some of the spam I've been getting...


jky