Longshaft on an Inflatable?

Little Rascal

Little Rascal

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Having considered all the options for a tender for a tiny yacht, I'm now thinking about getting an inflatable with a solid transom that will take my main outboard.

It's a Yamaha Malta 3.3 Longshaft which has a 'shallow water' facility where it can be locked at 45 degrees (ish) to run in shallow water. Its about 17kg.

Anyone used a longshaft on an inflatable? Any thoughts? How impractical is it likely to be?
 
It will do it, but it won't do it properly or well. At 45degs, you will be throwing water in the air, with the prop almost out of the water (I exaggerate only a little for the sake of emphasis)

Longshafts require a deep transom to be effective.
 
It wont drive properly in the shallow water position.

Put it fully down when the water is deep enough.

Take care when approachiing the beach, hard or slip way or you will keep whacking the bottom.

It may be a bit more difficult to start due to back pressure on the exhaust. That may be little more than a myth
 
Thanks. As long as it will run ok in 'deep' water... I'm trying to kill two birds with one stone: planning to have a bit of fun on local river/beaches where a 3 foot fin is a bit of an encumberance!
 
It becomes important with planing hulls where you want the AV plate pretty close to level with the bottom of the transom.
Higher then you'll likely get ventilation of the prop.

Lower and you have unnecessary drag.
 
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Wont work effectively - that is why outboards are made in two shaft lengths depending on transom heights. Long shaft on an inflatable is by definition 6" too deep. May cause problems of balance and lead to instability as well as possible difficulty in starting - which in turn leads to instability as you lean over the back trying to start it. Running at shallow water setting will not give you adequate propulsion, that is intended for temporary use.

If there was a compromise engine, the inventor would make a fortune - but there isn't.
 
The other issue is the the leverage from the longer shaft will try to twist the transom, tending to bend the inflatable into a comedy shape.
Might be OK at low throttle or with a very well pumped inflatable, but when the pressure in it drops a bit at slinging-out time.....

One of the best purchases I've ever made was a 2hp Yamaha 2 stroke for the tender. Very light, very economical and SWMBO can start it.
 
Not beyond the wit of PBO minded reader to bolt/wingnut another piece of plywood to the transom to raise the motor 4 or 5 inches?
 
I always used a long shaft Mariner 4 - the main engine on my Sonata - on my Avon dinghy to get to the boat. Sure, you had to be careful in shallow water and it weighed a bit more than was necessary but it worked perfectly well for many years. It also meant that the engine was used regularly rather than festering below decks corroding away whilst I sailed on and off the mooring. It also meant I could run fresh water through it after every use and store it upright ashore. As a result it lasted much longer than engines that stayed on board full time.
 
NickRobinson said:
err... see my pic?
Click to expand...

Hi Nick, that would be good... but your link takes me to the facebook log in page. Much as I'd like to see it, I'm not a facebooker... Post some pics here? Or image urls?



PeterR said:
I always used a long shaft Mariner 4 - the main engine on my Sonata - on my Avon dinghy to get to the boat. Sure, you had to be careful in shallow water and it weighed a bit more than was necessary but it worked perfectly well for many years. It also meant that the engine was used regularly rather than festering below decks corroding away whilst I sailed on and off the mooring. It also meant I could run fresh water through it after every use and store it upright ashore. As a result it lasted much longer than engines that stayed on board full time.
Click to expand...

Thanks Peter, that's exactly what I'm planning to do!
 
Going back to my youth... We used to use the Seagull Silver Century l/s on the 8ft rigid dinghy. Mostly fine, until I was off loading PX in Bray harbour in a F7. Trying to get off the lee beach to return to the boat, I rowed violently to get some depth, pulled the cord(started, natch) then engaged the clutch. The long lever arm of the L/S + me in the back, dunked the engine. More rowing, followed by a sort of ferry glide, got me back. I got a *******ing from my father for trying it ( but a sort of OK for pulling it off) The engine responded to the usual quick clean and was fine. It was the auxilary for our 27ft sloop.
So... Depth is the problem and leverage on a short tender.

Hey! First time I have activated the swear filter!!
 
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