Ribcraft 585 Auxiliary Engine?

JABS · 17 November 2006, 08:52

I have just bought a second hand Ribcraft 585 with a Mercury 90hp. I would like to carry an auxiliary for offshore trips. What size of engine do I need? I don't need to be able to necessarily contnue at speed, just get home or to safety. I would prefer to use a four stroke so that I can use the existing fuel supplies?
Any comments or advice would be very much appreciated.

BogMonster · 17 November 2006, 14:23

When I asked the same question a few months ago I was quoted 1hp per metre of boat as a general rule of thumb, and I therefore have a 6hp Johnson 4 stroke long shaft on my Humber 5.8. Having been out in a bit of wind with it, I'd not like anything less.... in a 20kt (ish) wind I get about 4.5kt into wind and about 5.5-6kt (GPS readout) downwind, but the real issue is not speed but control of the boat when the wind is catching you side-on, and it's a struggle to keep anything like a straight line even with the 6hp. You'll need to measure the transom to check shaft length, probably long shaft required as I doubt a standard short shaft will be long enough.

I bought a 4 stroke for the same reason, so I don't have to carry pre-mixed fuel on board and then worry about whether it has gone "off" or not. Lovely little engine (built by Suzuki and the same as the Suzy 6hp) if unused for a few weeks it needs 4/5 pulls to start it, and if its been running that day it starts first pull almost every time.

vince · 17 November 2006, 15:36

WE have a 4hp mariner 4 stroke which pushes along nicely at "get home speed." When its really windy, lock the aux in place, and use the wheel as normal, a bit more drag, but much better steering response.

JABS · 21 November 2006, 16:35

Thanks guys. Since more is better, I guess it will be 6HP!

codprawn · 21 November 2006, 17:13

I would be tempted with a 2 stroke - stands up to the abuse an aux gets better. Also they are stopping small carb 2 strokes so should be some good bargains about. A Tohatsu 9.8 would be ideal and is very light.

BogMonster · 21 November 2006, 21:24

Quote:

Originally Posted by codprawn

I would be tempted with a 2 stroke - stands up to the abuse an aux gets better. Also they are stopping small carb 2 strokes so should be some good bargains about. A Tohatsu 9.8 would be ideal and is very light.

What are modern two stroke hand start engines like to start? I know with Dad's old seagull when I was a kid, you needed to think about starting it the day before, to stand any chance of getting away vaguely on time

can't get better than my 6hp four stroke for starting and I think thats important for when you need it in a hurry!

codprawn · 21 November 2006, 21:26

Well my chainsaw starts first pull no matter what the weather!!!

BogMonster · 21 November 2006, 23:15

Quote:

Originally Posted by codprawn

Well my chainsaw starts first pull no matter what the weather!!!

Ah I see, so when your inflatable deflates you can teach the f***er a lesson? Sound thinking, in fact I might buy one myself

Poly · 21 November 2006, 23:39

Quote:

Originally Posted by codprawn

I would be tempted with a 2 stroke - stands up to the abuse an aux gets better. Also they are stopping small carb 2 strokes so should be some good bargains about. A Tohatsu 9.8 would be ideal and is very light.

I think you might be wrong... many yachties prefer 2-str (for various reasons - not least the storage on the side factor) and so there are rumours that people are buying or planning to buy 2str engines before the "ban" and will then sell them on after the ban (as second hand so legal

) at a profit.

ScottyDog · 22 November 2006, 08:39

With so many engine failures being attributed to fuel problems maybe having another fuel source for a 2 stroke outboard is not such a bad thing. Most of the 9.9 Hp models are also available in 15 Hp with the same weight. An extra knot may just make the difference between getting back against a current and not getting back at all.

JABS · 22 November 2006, 10:08

Some great points about two strokes. My concern is that I would need to carry a second fuel which would have a finite life. Two stroke deteriorates faster than petrol. Then, what to do with it when it is going off? Can't burn it in the car and don't have/want a lawn!

I already have two sources of petrol on board so am protected against fule tank contamination. My preference is still to stick with a four stroke.

Let the debate continue!

bedajim · 22 November 2006, 10:27

Quote:

Originally Posted by JABS

Some great points about two strokes. My concern is that I would need to carry a second fuel which would have a finite life. Two stroke deteriorates faster than petrol. Then, what to do with it when it is going off? Can't burn it in the car and don't have/want a lawn!

I already have two sources of petrol on board so am protected against fule tank contamination. My preference is still to stick with a four stroke.

Let the debate continue!

My plan is to have a 15hp 2 stroke and a 20 litre fuel can/tank as a reserve, not mix the oil/petrol until i need it but have a plastic bottle with the 2 stroke oil pre-measured so open the tank tip it in and off you go

15 hp so I can get home against the tide and wind

20 litre of spare fuel for the main engine

quick mix and go for the two stroke if needed
and a good anchor

James

codprawn · 22 November 2006, 12:35

Quote:

Originally Posted by JABS

Some great points about two strokes. My concern is that I would need to carry a second fuel which would have a finite life. Two stroke deteriorates faster than petrol. Then, what to do with it when it is going off? Can't burn it in the car and don't have/want a lawn!

I already have two sources of petrol on board so am protected against fule tank contamination. My preference is still to stick with a four stroke.

Let the debate continue!

Don't mix the oil until you need to. Also why should a 2 stroke mix deteriorate faster? It's still the same petrol.....

BogMonster · 22 November 2006, 14:24

Quote:

Originally Posted by codprawn

Don't mix the oil until you need to. Also why should a 2 stroke mix deteriorate faster? It's still the same petrol.....

Personally the last thing I'd be wanting when the fan stops and I'm drifting towards rocks in a 20kt wind and a bit of a sea, is to be buggering around mixing fuel and tipping oil all over the floor (or trying to attach the engine to the transom for that matter).

If I'm going anywhere I might need it, the aux is on the transom fully fuelled and ready to go and has a test run before I go. I should be able to get it running within 30 sec if needed.

Before anybody points it out, the fact that I am mostly not going anywhere due to the effin Humber Self-Destroyer having a(nother) hole in it is neither here nor there