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Old 01 May 2006, 05:42   #11
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Our A frame is designed for wakeboarding, we were pulling up 2 monoskiers last summer without any problem - I'll give you a tow at Ribex if you like Roy!
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Originally Posted by Zippy
When a boat looks that good who needs tubes!!!
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Old 01 May 2006, 11:37   #12
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Folding Frames

I am looking to keep my new rib in my double garage but I am limited by height So I'll either need an A frame that is low, removable (easily) or a folding pole that I can fold down for storage. Any ideas? Also if you know the height of the top of your A frame when the RIB is on the trailer that could help in my plans. Cheers
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Old 01 May 2006, 14:02   #13
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a frames

Not all A frames are the same
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Old 01 May 2006, 14:58   #14
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Wakeboarding

If you use a high rope position to wakeboard or monoski , do you need to put extra weight in the bow to keep the nose down?
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Old 01 May 2006, 15:08   #15
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I dont seem to need any
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Old 01 May 2006, 15:13   #16
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Quote:
Originally Posted by Under the Thumb
If you use a high rope position to wakeboard or monoski , do you need to put extra weight in the bow to keep the nose down?
Eh?! Not heard of that one before. If the bow did rise surely a dab of the trim switch would cure it?
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Old 01 May 2006, 20:06   #17
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Quote:
Originally Posted by Tim M
I have double A frames on two of my RIBs. Would not hessitate about towing off either of them. In answer to your question they are bolted through the transom, and through the deck.


I should hope the a frame is bolted through the transom and the deck, however what are they bolted to under the deck, a threaded insert or an under deck plate?
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Old 04 May 2006, 04:39   #18
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This could be controversial....

NEVER EVER tow from an A frame unless you have the manufacturer's certification to do that - and I mean from the hull manufacturer as well as as the frame builder.

By all means run a rope over or through the frame for towing, preferably using a bar to keep the rope out of the prop's way.

The end of the tow line, however, should be attached to a purpose built towing cleat on the deck, or even better tow via a bridle. This provides a number of advantages, and is good practice even if your frame is rated for towing -

1. By passing the rope over the frame, it puts the frame in compression rather than the tow line acting against the frame's joints and strength.

2. If you need to jetison the tow rapidly in an emergency, the helmsman or crew can cut the rope by the cleat (ensuring no-one is in it's recoil line) a lot quicker than you could if you had to climb onto the frame first.

Simon
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Old 04 May 2006, 08:30   #19
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A couple of summers ago we were in Cyprus, and they were towing 6/8 man bananas from the A-Frame of a 6.5m RIB (Humber?). They had mounted it at the top of the A-Frame to make sure that the tow line stayed clear of the prop, but they had then run additional lines from the top of the A-Frame to the cleat at the bow of the RIB to support the A-Frame (the only people on the RIB were the crew - no passengers usually).

When stationary the lines weren't hanging loose, but were 'tight' like a guy rope of a tent (i.e. you could move them up and down a bit). Once under way and towing, the lines were rigid - and I was uncomfortable sitting anywhere near them!!

ANYWAY - my point - the forces applied to the top of the A-Frame are very big - hence the movement in the A-Frame and tightening of the ropes that were supporting it. I'd rather use the towing eyes than just tie to my A-Frame - unless the A-Frame is designed for it.

My towing bridle is just a piece of 3-strand nylon line spliced onto carabiners - but I've put some bungee cord through the 3-strand and clip that onto the A-Frame - when not under load the bungee pulls the rope up and away from the leg - and when under load, the bungee is stretchy enough that it lets all the load go to the towing eyes and not up to the A-Frame. I've not used it that much, but when I do, I haven't managed to foul my prop (yet ).

D...
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Old 04 May 2006, 12:03   #20
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It's a simple matter of geometry - if you are towing off the top of the A frame the twisting force on the transom will be huge compared to if you are towing off the A frame just above the transom, for example.

I wouldn't even think of it on mine, it would break off immediately, but then mine isn't designed to stand up to that, it is a DIY job, built for a set of nav lights not a lardy person with their butt wedged into a tractor inner tube
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