Long or Short Shaft

[happyfish]

I have a Hurley Silhoutte and it is in need of a new outboard. As the boat is new to me and I am unable to visit the boat at the moment to take measurements.
I was hopeing some of you clever people might know what kind of outboard I should buy.

Long shaft or short shaft,

2 stroke or 4 stroke

many thanks eddy.

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[jhr]

SailbadtheSinner (on Scuttlebut) has an interest in a Silhouette and will probably be able to help if you send him a P.M. I think he has mentioned something about having a long shaft Seagull in the past.

Being a Scouser, he may be able to advise you about the best place to nick one from, as well. /forums/images/icons/smile.gif

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[whisper]

I also would expect it to need a long shaft. I'd also go for 4stroke as they are less likely to splutter to a halt when doing slow speed manouvres. They are also quieter but heavier than 2strokes.

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[tamarnessie]

I'd say a long shaft from experience. I originally had a short shaft on my 17 footer but found the prop always came out of the water in any sort of swell.
I use a 2 stroke, but that's more to do with a lack of funds than it's performance! Its also easier to lift off the boat on my own.

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[oldharry]

The key thing is the height of the bracket above the water. A short shaft engine must not be mounted more than 16 inches above the water, measured from the top of the transom or bracket mounting pad. A standard long shaft requires a maximum 20 inches.

It is usually best to use a long shaft engine so that the prop will go deeper into the water, so not be lifted out so easily, and the 4 inches extra length makes a surprising difference to the number of times the engine gets dunked in rough water. However, the deeper the prop is immersed, the greater the back pressure in the exhaust, and this can in extreme situations cause starting problems, particularly with very small engines.

If you try to use the engine higher out of the water than is intended, the prop will easily cavitate.

Remember too that on a small boat, the weight of the crew going forward to anchor will lift the engine, and cause it to at least cavitate, and in the case of a very heavy crew (me for example) canlift the leg far enough to stop the intake of coolant water. Not a good idea!

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[William_H]

No question buy a long shaft. It will be better for all the already stated reasons and if mounted higher will be more accessible for starting and trouble shooting. Do you have an adjustable height bracket? They can be good to lift the motor a little for starting then drop the motor for situations with someone on the foredeck or if you have cavitation problems. My boat being light has a huge variation in transom freeboard and a adjustable bracket is the answer.

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[blue_anchor]

long experience with o/bs..imho,go for a tohatsu long,5hp on a cantilever bracket,i got a good deal from marine scene,if you intend to keep the boat for a while,go for a new o/b,false economy s/h,but never let the o/b mix hang around.

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[Avocet]

Long shaft - every time! We had a 22 footer with a Mariner 5hp long shaft and even then it would loose its grip on the water as the boat pitched in a swell. A short shaft would have been even worse!

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