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Old 07 October 2005, 10:14   #1
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What power auxiliary outboard for 6.5m?

I'm planning to extend my cruising ground next year. I hope this will include The Isles of Scilly, The Channel Islands and further along the South coast. I'm based in the Solent.

I have a 2.5 hp Tohatsu that I could mount on the transom. What sort of speed would this give me in the event of a main engine failure? What auxiliary outboard hp would I need to produce 4/5 knots?

Rich
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Old 07 October 2005, 10:21   #2
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Quote:
Originally Posted by rbw156
I'm planning to extend my cruising ground next year. I hope this will include The Isles of Scilly, The Channel Islands and further along the South coast. I'm based in the Solent.

I have a 2.5 hp Tohatsu that I could mount on the transom. What sort of speed would this give me in the event of a main engine failure? What auxiliary outboard hp would I need to produce 4/5 knots?

Rich
just based on what you see on the river i would go for a 4 or 5 hp as a 2.5 might be a real limp home and if the water is against you or the wind you might go nowhere fast

a sib dont go very fast with a 2.5 on the back so a 6.5 rib will be very interesting
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Old 07 October 2005, 10:23   #3
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Alderney

Has anyone crossed over to Alderney from the Solent?
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Old 07 October 2005, 10:25   #4
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Yes, a few times!

Why do you ask?
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Old 07 October 2005, 10:27   #5
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I haven't even got my rib yet, but I would love to do that trip. A quick pint in the Divers!

--Andy
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Old 07 October 2005, 10:29   #6
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Andy

Have a look at
http://ribsters.proboards22.com/inde...6469165&page=1

for an ongoing account of The Jackeens and co trip this summer.
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Old 07 October 2005, 10:36   #7
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one of our trips is fairly well documented here:

http://www.rib.net/forum/showthread....alderney+jaunt

HTH!
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Old 07 October 2005, 10:58   #8
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Well, I'd certainly be up for a group trip to Alderney. There is always safety in numbers!

Rich
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Old 07 October 2005, 11:29   #9
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How long would it take? 3hrs?
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Old 07 October 2005, 11:37   #10
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Depends how fast you go

Yep, allow three hours from Needles in good conditions. You'll end up stopping for one reason or another... change of helm, cup of tea, comfort break, hopefully not a net caught round the prop!
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Old 07 October 2005, 11:42   #11
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Quote:
Originally Posted by rbw156
I'm planning to extend my cruising ground next year. I hope this will include The Isles of Scilly, The Channel Islands and further along the South coast. I'm based in the Solent.

I have a 2.5 hp Tohatsu that I could mount on the transom. What sort of speed would this give me in the event of a main engine failure? What auxiliary outboard hp would I need to produce 4/5 knots?

Rich
When I sold Seahawk 1 (a Parker 630 diesel ) the new owner insisted on having an auxiliary engine on the transom and a 5hp outboard was fitted. The max speed was 5knots. I do not think you will get far on a 2.5 HP
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Old 07 October 2005, 11:49   #12
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Quote:
Originally Posted by Andre
When I sold Seahawk 1 (a Parker 630 diesel ) the new owner insisted on having an auxiliary engine on the transom and a 5hp outboard was fitted. The max speed was 5knots. I do not think you will get far on a 2.5 HP
in fact i would venture to say a 2.5 would not pull the skin off a rice pud!!
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Old 07 October 2005, 12:06   #13
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1hp per meter is quite a good rule of thumb
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Old 07 October 2005, 12:20   #14
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Hi
Ive got a 8HP Tohatsu Aux on my 5.8 Mtr Narwhal when I tested it I made 6 Kts in slight seas.

Shaggy
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Old 07 October 2005, 12:53   #15
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Quote:
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Yep, allow three hours from Needles in good conditions. You'll end up stopping for one reason or another... change of helm, cup of tea, comfort break, hopefully not a net caught round the prop!
We have got a net caught around our prop *twice* in consecutive years, at the top of the Alderney Race!
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Old 07 October 2005, 17:08   #16
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easy trip really we did it again a couple of weeks ago to cherbourg and St vaas on ours andwhiteshoes on his boat 2 hours ish back three hours ish there. Alderney during the summer as per Marks link 3 hours.

not much more really than a trip around the iow 60 miles give or take.

Just make sure you have the right heading or ya might end up going in the wrong direction as happened when on board another boat

will dig out some links later.

BruceH has an aux on his solent 6 hp i think which will push him at 6 kts. Our aux is sea start and the other boats we go out with.



paul
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Old 07 October 2005, 17:20   #17
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Real Auxillary

RBW


Remember what an auxilary is going to have to do for you.

On a calm summers day you will have few worries and plenty of other boats to come to your assistance.

An auxillary is for the day you get into a spot of bother, possibly with family on board, possibly with a bit of weather and often with some miles to go from home.

Hence forget the hair dryer style auxillary and go for something that will get your boat under way in a heavy sea. Small outboards are not up to the job in anything but a flat sea.

Redbay fit 15 hp on their 6.5 m on the basis that the bigger prop is needed to get a grip in the water. Alternatively you could go for something like the high thrust yamaha 8hp which has a reduction gearbox and bigger prop to give you plenty of thrust v hp .

Probaly be a good idea to talk to users of the same size and make of boat as yourself, then borrow a few enginnes to try out which suits best. Remember to test in foul weather.

rgds

peter
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Old 07 October 2005, 17:23   #18
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Just make sure you have the right heading or ya might end up going in the wrong direction as happened when on board another boat paul
205 ish?
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Old 07 October 2005, 20:12   #19
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I once swapped a merc 7.5hp short shaft to a merc 4hp longshaft big foot on a 22ft sailing yacht and it was just as quick with a reverse that worked to boot,I think where a boat is heavy enough not to plane with the power available,(the auxilary)its a good plan to have a prop designed for slower speeds as it grips better so maybe you can get better thrust from a more manageable size of outboard.
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Old 07 October 2005, 20:43   #20
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1hp per m not enough

High Rich

important to have aternative propulsion.

we have 6 hp suzuki on 6.3m humber.

It was not enough when the main engine leg failed.

would now run 15hp on this size boat.

Afterall any auxilary will push you around a harbour but out at sea is different.

Paul
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