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Old 27 January 2014, 17:43   #1
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room for aux?

Hi I want to fit an auxillary engine to my Ribcraft 4.8 I would hate to have to call for help if the main Mercury 60 (1996) packs up!
Looked at Torqueedos as they are very slim but to get a decent amount of range you need a whacking great battery and they are expensive.
The plan is to get the 60 serviced and learn the basics on it, then fit a new 5 or 6hp alongside. I like Suzukis and im guessing the 6hp as its the same size and weight as the 4/5 hp. Anyone know how wide they are?
Theres not much room with the steering cable/arm and controls and also an A frame I dont really want to lose.
So a bracket mounted on the transom then. Would it matter if it were as much as 10inches behind the transom for steering clearance?
A custom bracket made by somebody?
Would I be able to lift it on fairly easily(26kg) or only mount it beforehand?
Are ANY of the ready made brackets worth considering?
I like the idea of the engine being upright and sturdy and then lowered down a bit when needed.
Any advice gratefully received before I attempt this.
Ta
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Old 27 January 2014, 17:57   #2
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Check out the size of the 3.3 mariner (and may be the same engine but made by other brands) a little on the small size but it depends where you do your boating?



I've seen some carry an aux on the transom and strap the leg up to the aframe so it doesn't move about.

Have a measure of the transom height too as you may just need a short shaft in the offset location so you could use it on a sib too
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Old 27 January 2014, 18:16   #3
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oh good thinking about the transom height!
That 3.3 is really light 13kg! would it push me along against any sort of current?
i want it as a get me home mainly but would also be used pottering up estuaries on holiday.
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Old 27 January 2014, 18:21   #4
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Originally Posted by gary222 View Post
oh good thinking about the transom height!
That 3.3 is really light 13kg! would it push me along against any sort of current?
i want it as a get me home mainly but would also be used pottering up estuaries on holiday.
If you send a PM to Downhilldai and ask him, I'm sure he runs a Avon Searider 4.7 with a 2" Biffer Aframe with a 3.3 mariner aux. He's not the type of guy to get things wrong
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Old 27 January 2014, 18:29   #5
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I would hate to have to call for help if the main Mercury 60 (1996) packs up!
Just reread your 1st post, if you do go for a 3.3 you should be able to get a merc to match your 60 Not important but it looks cool

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Old 27 January 2014, 18:31   #6
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oh good thinking about the transom height!
That 3.3 is really light 13kg! would it push me along against any sort of current?
i want it as a get me home mainly but would also be used pottering up estuaries on holiday.
I used a 2.5hp on a 4m searider.
I never had to use it in anger but it moved it all be it at a relaxed pace it a 4ft swell and against river current ok.

To fit it I put a piece of mahogany to one side of the A frame fixed with a stainless U bolt around the A frame.
I turned the engine around and re fitted it on the mahogany 'bracket' when not in use and strapped it down the side of the main outboard fuel tank so the prop was on the deck of the boat.
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Old 27 January 2014, 18:43   #7
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Thanks, all good ideas!
Maybe a smaller engine will suffice
Ill get my tape measure out and have a think
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Old 27 January 2014, 18:51   #8
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Thanks, all good ideas!
Maybe a smaller engine will suffice
Ill get my tape measure out and have a think
Nos is also good with Aux ideas

I think the rule of thumb is 1hp for every 1m of rib length so for you it would be 4.8 hp (5hp) but it would be good to hear from someone who runs a similar set up
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Old 27 January 2014, 18:52   #9
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Make: Ribcraft 4.8m
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Engine: Tohatsu 60hp + aux
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I did the same thing on my Ribcraft. I go to the west coast of Lewis most summers, and being without an auxilliary engine isn't an option, given location, lack of other boats in the area, changing sea state (always a bleed'n swell in the Atlantic).

I don't have an A-frame, as my boat is stored in a garage, so I opted for a bespoke stainless steel light pole. This frees up quite a bit of space. The steering drag-link on the port side rules out fitting an auxilliary on that side. I mounted the auxilliary engine straight onto the transom. I used to have a Plastimo adjustable bracket on a previous boat and it was a complete disaster, it rattled like a bag of spanners.

I have a Mariner 4hp 2-stroke auxilliary. I opted for a long shaft, but it may be possible to fit a standard shaft instead. The benefit of the long shaft is that there's no chance of cavitation in a rough sea, it'll stay firmly planted.

I also fitted a stainless steel 'U' bolt on the transom knee. I use a mini ratchet strap around the power head of the auxilliary, then through the starter rope aperture and onto the securing bolt. When it's tensioned its rock solid. If you don't secure it there's a real possibility you'll damage the outboard, tilt bolt, etc.

Choice of auxilliary is key, with weight, service costs, and of course overall dimensions. Might not be such an issue if you opt for a bespoke fixed bracket extension. A Yamaha or Tohatsu 5hp 2-stroke would be perfect in my opinion. The Tohatsu M5B is 21kg, and the Yamaha M5CMHL is 21.5kg, and both have plenty grunt, but might be overkill for what you're looking for.
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Old 27 January 2014, 18:58   #10
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Another picture, this time with the light pole so you can see space available.
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