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Old 23 September 2011, 11:34   #21
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Thinking out of the proverbial box for a minute, where is your steering cable relative to the aux clamps when installed? (could measure clamp height on the Port side & compare with the toob) . I know this will be a right royal PITA, but if it is above the clamp screws when the aux is installed, I bet you could remove the steering toob, fit the aux, then reinstall the steering over the top of the aux clamps. Worst case loosen the engine bolts to get the Aux clamp past, and reinstall. The steering toob over the top of the clamp would also make it more difficult to nick!



Or for the maximum hassle, if we are on the subject of unbolting the main, all the talk of raising engines by a hole for better performance etc, could you "jack" the main up a hole so the steering bowden clears it completely?
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Old 23 September 2011, 12:04   #22
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I got lost in all the posts a long time ago but I have a new 2011 3.5hp Tohatsu which has only used 1 tank of petrol - didn't need it in the end It also has an extension throttle/steering arm so you can control the steering and throttle when you are further up the boat .

Details are in the for sale section somewhere but perhaps I ought to keep it as an auxiliary for my proposed RIB but I shouldn't really need one for local trips and modern engines are very reliable!! - shame to sell it though lovely engine........
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Old 23 September 2011, 12:07   #23
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Old 23 September 2011, 12:23   #24
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Just an observation re the steer with the main engine and use the aux to just push you concept.

I had an engine stop on a twin rig rib and the drag of the one stopped one in the water was stunning. Even with another 200+hp of good engine I could only get to 14knts ish with the stopped engine in the water.

Once lifted it was like taking the brakes off and we popped up to 20+ easily.... now consider this as I had a worlds biggest aux engine ( ok maybe not propped right ) ....

If I'd 'only' had 5-10hp ( allowing for the prop set up etc) the main engine still being pulled through the water with the prop spinning freely would make a BIG differance to how quickly I could get places ( or away from nasty places).

Just my 2p....I'll get my coat .......
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Old 23 September 2011, 12:44   #25
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understood pete, but 5hp not gonna get you planing anyway, faster the speed the more effect the dragging leg will make, at displacement speeds i dont think the difference would be that dramatic?
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Old 23 September 2011, 12:54   #26
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understood pete, but 5hp not gonna get you planing anyway, faster the speed the more effect the dragging leg will make, at displacement speeds i dont think the difference would be that dramatic?
defo agree. I guess just more an question of trying it to see if people are happy with it and know what will happen when a main engine stops and the aux is made to earn its place.

Maybe we need a 'RIBNET try my aux engine day' so people can offer things up, without having to buy then can see what works/fits etc ?

Pete
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Old 23 September 2011, 13:21   #27
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How about about using an oar or a paddle as a rudder ,
you could just lash it to the transom and steer with that leaving the engine running straight .
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Old 23 September 2011, 14:00   #28
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i'm not concerned at all folks about steerage, i just want it to tilt. i'm happy to use the main to steer it if need be.

my old man has the engine so i'll goto the boat tomorrow and get plenty of pics of the various mounting options and go from there.

thanks for input anyway folks.

cheers
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Old 23 September 2011, 18:41   #29
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Aux bracket gets my vote.
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Old 23 September 2011, 20:53   #30
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understood pete, but 5hp not gonna get you planing anyway, faster the speed the more effect the dragging leg will make, at displacement speeds i dont think the difference would be that dramatic?
I have tried it (thinking the same thing). Last time I was out I had a good run around on the aux to burn up the six month old fuel, and during that I wondered if it would help the speed if I pulled the main engine up. Main up or main down made very little difference to the speed - maybe a quarter of a knot tops. You can compromise and tilt the main up so there is just the skeg trailing in the water, and you still have most of the useful steering input but a bit less drag.

I think aerodynamics say that wind resistance increases as the square of speed (which is why you need a lot more power to get a bit more speed), so if hydrodynamics are the same, that would explain it.

You can also spin the boat on the spot by using the aux full ahead and the main slightly astern, yes it was a nice day and no I had nothing better to do than pretend I had real twins
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