Auxillary engine size advise please?

[111KAB]

I have a small 15 ft speedboat with a 50hp Mariner. Just returned from a break in Mallorca when my engine let me down (now sorted) and had to call someone out to pull me in. Decided to fit an auxillary outboard "just in case" but unsure what size I need as nearly all the boats in the marina were covered up. Really just want the smallest 2 stroke petrol, not new but reliable and want to buy in UK and take out with me. Realise there are many factors to bear in mind but furthest I will probably be from 'safety' is 5km and heaviest load will be 3 people in calm seas. Advise please. THANKS (Again!)

 

[Canopy Locked]

With a small boat - weight will be a major issue (assume you have space for an aux bracket?) I believe that the Tohatsu engines are great value for money and one of the lower weight engines - would have thought that something a 4hp 2 stroke should be adequate

 

[Davy_S]

I use a 15ft boat for fishing, in the tideless waters of the med a 3.3 evinrude pushes me along at 4 knots easily, it will get me home no probs if the main engine fails.

 

[l'escargot]

A Tohatsu 3.5 2 stroke would be up to the job if you can get hold of one. Won't get you home quick, but is reliable and will put up with abuse and infrequent use.

 

[Csail]

We have a 14' with 4hp second outbd which works well.

 

[ontheplane]

Don't get confused between POWER and Thrust.....

For example - they used to tow 1000ton barges along canals with exactly One Horsepower.....

What you need for an auxilliary is thrust, and for the boat you're describing not that much of it, but a standard outboard is designed to reach maximum revs and max speed on the boat it's designed as a main engine for (so in the case of 3hp engines, that means a super light inflatable....

What you need to look for is a Sailpower engine. These are totally different in that they have a lower geared lower end and a totally different prop.

If you can't find one, I suggest you at the very least try and get a hi-thrust prop for a standard outboard.

Search the thread for "Sailpower" and you'll find a load of threads on this. In reality, you only need about 2-3 hp, but you do need a hi-thrust propellor to turn that power into thrust most efficiently at the speeds you'll be travelling at.