how big an auxillary engine?

[petevolvo]

Any advice? I run a little Beneteau Flyer (5.5mtr) with a 115hp Suzuki outboard. Boat has an an auxillary bracket but I've yet to get a 'get you home' motor. What size would I need? I've been told everything from 3.5hp - 15hp (which is far to large for the boat - I'll be getting a crick in my neck from leaning over so much). The boat is used around the North East Coast and within 5 miles of shore - I'm tempted to just get a small 3.5hp unit as a 'just in case' measure to keep weight down but am concerned that it wouldn't be up to the job. Any advice would be helpful.

 

[Talbot]

The important question is where do you run the boat. The 3.5 would certainly push the boat, but not very effectively against tide or adverse weather. If you can find one a 2 stroke tohatsu 9 hp would be a good compromise.

 

[colingr]

I agree, I had a 6 hp on my Maxum which was fine unless we had to puck the tide. 9 would be good.

 

[Channel Ribs]

There are still some 5HP two strokes around, let me know if I can have a look for you.

 

[JasonB]

I have a 21ft Bayliner and picked a 5hp johnson as it was the same weight as the 4hp. Also as a 4 stroke it would take "neat" petrol without me having to oil it on a bucking boat on the day when I really needed it and I could use the main petrol tank as backup to feed it in a worse case scenario.

It seems to move the boat ok in the kind of weather I go out in (usually sunny) or on the days when the weather is not so good I never leave the Harbour so the chop is never too much (Cork Harbour has a lot of room!)

My main engine is a Yamaha 125 (I think - it's been 6 months since I used it I can't remember it's hp! /forums/images/graemlins/blush.gif) and, touch wood, it hasn't let me down. I run my backup engine every time I'm out to make sure it's in running order.

J.

 

[ontheplane]

You don't need more than 9.9hp.

As an aux you should look for a sailpower motor if you can - so many people confuse power and thrust.

To get on the plane you need power and thrust - but as an aux all you need is thrust, albeit plenty of it!

A 5hp sailpower will probbly push your boat at around the same speed as a 10hp conventional motor would - however put them on a tiny RIB and the 10hp would be MUCH faster - why?

it's all down to the prop size, shape and pitch.

A 5hp Sailpower will push a 25ft sailboat, and reach 5kts or so because t will run up to max revs whereas a 10hp normal outboard will "bog down" and might only reach half revs - so might only be producing about 5hp anyway!

 

[petevolvo]

Feeling stupid but 'what's a sailpower'?

 

[whisper]

Sailpower engine either has a different final drive ratio or a different propellor. This is to make it more efficient at pushing heavier boats at slow speeds.