Back-up Outboard ?

Quickflash · 08 December 2007, 18:38

What would be a good outboard engine to use as a back-up outboard incase my Scorpion 9,75m with the Volvo 370 DPR inboard diesel fails on me ? It needs to be light weight and small ( to be stored in the engine bay) but powerfull enough to bring me home if needed (at a slower pace) . I searched other threads but could not find any recent thread on this topic. I am considering the Yamaha 8 Hp 2-stroke. Any comments ? Thanks

Searider · 08 December 2007, 19:06

Probably best looking at the high thrust, long shaft, models made for sailboats. 9.9hp ish.

v666 · 08 December 2007, 22:04

I use a Yamaha 15 Hp 2-stroke on a Ribeye 785, IMHO it's only just enough.

We had a rope wrap around the main engine prop in very thick fog (about 30m vis) with tide and wind pushing us onto the rocks.
It took about 20 mins to free the main prop and we had the 2 stroke running at about 3/4 top speed.
When we got home I looked at the data from the plotter. We moved very little from where our engine cut out which quite surprised me.

I would not want anything less than 15HP as a backup, and I hope I'm not caught short in anything but a moderate sea/weather.

Tim

codprawn · 09 December 2007, 00:59

Quote:

Originally Posted by Searider

Probably best looking at the high thrust, long shaft, models made for sailboats. 9.9hp ish.

I agree - thrust at low speed is more important. I have seen old Seagulls outperform more powerful modern outboards for this very reason!!! Don't buy one though...........

Limey Linda · 09 December 2007, 01:29

Quickflash
Please bear in mind that 4 strokes do not like being stored in the engine compartment on their side. The sump oil goes where it should not be. Also, for 9.9 engine you are talking at least 90 lbs wet, if it is a 4 stroke and 60lbs. for a 2 stroke, + fuel tank You will have to haul it out and mount it on it's bracket, hook it up and start it. Somewhat difficult to do in any sort of rough conditions. If a 2 stroke you will have to change the pre-mix fuel regularly and run the engine. If were me, I would permenantly mount a 15hp
4stroke on a bracket and hook it up to portable tank so it is easy to use and check.

joakimhansson · 10 December 2007, 08:55

Quote:

Originally Posted by Quickflash

What would be a good outboard engine to use as a back-up outboard incase my Scorpion 9,75m with the Volvo 370 DPR inboard diesel fails on me ? It needs to be light weight and small ( to be stored in the engine bay) but powerfull enough to bring me home if needed (at a slower pace) . I searched other threads but could not find any recent thread on this topic. I am considering the Yamaha 8 Hp 2-stroke. Any comments ? Thanks

Do you have any pics on your rib?

Quickflash · 10 December 2007, 11:27

Quote:

Originally Posted by joakimhansson

Do you have any pics on your rib?

Not yet, I will take delivery of the Rib in March. I am just preparing for any eventualities whilst the Rib is still in build-phase.

Quickflash · 10 December 2007, 11:29

Quote:

Originally Posted by Limey Linda

Quickflash
Please bear in mind that 4 strokes do not like being stored in the engine compartment on their side. The sump oil goes where it should not be. Also, for 9.9 engine you are talking at least 90 lbs wet, if it is a 4 stroke and 60lbs. for a 2 stroke, + fuel tank You will have to haul it out and mount it on it's bracket, hook it up and start it. Somewhat difficult to do in any sort of rough conditions. If a 2 stroke you will have to change the pre-mix fuel regularly and run the engine. If were me, I would permenantly mount a 15hp
4stroke on a bracket and hook it up to portable tank so it is easy to use and check.

Limey Linda, good point, hadn't thought of this yet. thanks

Julian · 10 December 2007, 15:11

Quickflash

When Scorpion built our boat, Graham built a engine mount in the engine compartment so the spare outboard could be stored in the correct position with fear of damage. On the stern we had a bathing platform fitted with a built in stand to take the outboard, it just bolted straight on very quickly. There was also a spare fuel tank built under the seat with a lenght of pipe set to plug straight in so it was very simple.

It would still be tricky in the rough but its something you may want to look into. We didnt have one mounted permantly as we have seen so many smashed to bits after a while.

Hope thats of some use to you

Cheers

Julian

Quickflash · 10 December 2007, 15:27

Quote:

Originally Posted by Julian

Quickflash

When Scorpion built our boat, Graham built a engine mount in the engine compartment so the spare outboard could be stored in the correct position with fear of damage. On the stern we had a bathing platform fitted with a built in stand to take the outboard, it just bolted straight on very quickly. There was also a spare fuel tank built under the seat with a lenght of pipe set to plug straight in so it was very simple.

It would still be tricky in the rough but its something you may want to look into. We didnt have one mounted permantly as we have seen so many smashed to bits after a while.

Hope thats of some use to you

Cheers

Julian

Certainly, thanks, what kind of outboard do you use and does it have sufficient HP's to do what it has to do ?

Julian · 10 December 2007, 16:13

We had a selva 9hp which to be honest we have never had to use, I think it would push the boat along but not very well and especialy if there was a tide running etc, I would have thought a 15hp would do the trick.

Cheers

Julian

Slaphead · 11 December 2007, 20:08

I used to carry a Yam 15hp 2 stroke on my P22 which was a PITA because I had nowhere to store it. Pushed the boat along at 6 knots... heavy engine.

I then carried a brand new High Thrust 8hp which was an even bigger PITA because due to it's length it could only sit at the bows and at 42kg you needed to have arms on you like Popeye to move it about- never mind trying to attach it to the transom when rolling about. Never used it.

Have you thought about getting a cheapie 6hp and uprating it to a 9 or 10?

Chris · 12 December 2007, 14:27

I think the point of an aux is it needs to be there when you need it. The 2 times I have needed to use mine had it not been on the transom and ready to run in a matter of 10 seconds I would have been pushed onto the rocks of the island we were stopped at to watch some wildlife.

I view an AUX as something that can be quickly deployed to give you steerage and enough speed to move you away from immediate danger so that you can drop anchor and sort out your main engine or get the coastguard on the radio.

I get 4 knots max out of a Yamaha 4HP with a high thrust prop on a 5.5 meter RIB the engine weighs in at 22KG and is always there when I need it. Because its easy to drop in the water and run I am more inclined to do this most times I go out, so as to ensure that when I do need it I won't be worrying whether its going to start and run OK!

Chris

BogMonster · 13 December 2007, 10:50

Quote:

Originally Posted by Chris

I think the point of an aux is it needs to be there when you need it. The 2 times I have needed to use mine had it not been on the transom and ready to run in a matter of 10 seconds I would have been pushed onto the rocks of the island we were stopped at to watch some wildlife.

I view an AUX as something that can be quickly deployed to give you steerage and enough speed to move you away from immediate danger so that you can drop anchor and sort out your main engine or get the coastguard on the radio.
Chris

Me too and like you the only time I have had to use it in anger, I barely had time to start it and avoid the rapidly approaching rocky beach and jagged rusty shipwrecks (strong onshore wind) when the main engine cut out. Mine lives on the transom, it doesn't get started every time I go out but I always give it a run if I am going any distance to make sure it will go when I need it to, and I try to run it for half an hour or so every couple of months just to make sure it stays happy.

When my father was being taught to fly, the instructor told him there were three things which were useless to any pilot in an emergency: runway behind you, height above you and fuel in the bowser. An emergency aux which you can't use in a hurry sort of falls into the same category on the water

danwells · 13 December 2007, 11:36

Quote:

Originally Posted by Quickflash

What would be a good outboard engine to use as a back-up outboard incase my Scorpion 9,75m with the Volvo 370 DPR inboard diesel fails on me ? It needs to be light weight and small ( to be stored in the engine bay) but powerfull enough to bring me home if needed (at a slower pace) . I searched other threads but could not find any recent thread on this topic. I am considering the Yamaha 8 Hp 2-stroke. Any comments ? Thanks

yes thats about right or a 9.9 hp yamaha two stroke

bedajim · 14 December 2007, 07:18

Quote:

Originally Posted by danwells

yes thats about right or a 9.9 hp yamaha two stroke

I would think a litle bit small

I have a 15hp 2st on my 6.5 and get 8 knts, main engine down used as rudder

Limey Linda · 14 December 2007, 15:38

Quote:

Originally Posted by danwells

yes thats about right or a 9.9 hp yamaha two stroke

I think 9.9hp on a 9.75 m. boat is far too small to be useful. What do you base your suggestion on?

Locozodiac · 27 December 2007, 03:31

If instant portability and low engine weight is required in an emergency, how about a Tohatsu 05 HP 2 stroke engine, short or long tail fitted with a high trust 7" propeller or a bit lower. The standard factory prop is 8". This small engine can push a Otmimist Class sailboat and crew that weights 2 tons without any trouble. Comes standard with an internal 3/4 gal and external 3 gal gas tank. Just an idea...

Limey Linda · 27 December 2007, 04:00

Quote:

Originally Posted by Locozodiac

If instant portability and low engine weight is required in an emergency, how about a Tohatsu 05 HP 2 stroke engine, short or long tail fitted with a high trust 7" propeller or a bit lower. The standard factory prop is 8". This small engine can push a Otmimist Class sailboat and crew that weights 2 tons without any trouble. Comes standard with an internal 3/4 gal and external 3 gal gas tank. Just an idea...

I know where you are coming from on this. I had a 26ft sailboat with a 6 hp and it would punch through anything at hull speed. About 6 knots. However, we must remember that planing hulls are grossly inefficient at displacement speeds so a larger engine is needed to compensate.