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Old 05 January 2015, 05:05   #1
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Towing bridle

I've been looking at the Turboswing and read the write up in a recent PBR. It's a nice idea but the price is prohibitive for the occasional towing work that I do.

Would a free-running pulley, similar to the Turboswing pulley, but just on a rope bridle between transom eyes, be effective? My idea for a cheap towing arrangement that improves on just using a cleat was to make a bridle between the transom eyes (or even the A frame cleats) that is just too short to get tangled in the prop, and then use a pulley to attach the tow line so it can run up and down the bridle fairly freely even under load.

I assume the major benefit of the Turboswing is that the geometry and shape of the frame mimics the tow line extending to either the pivot point of the outboard, or in front of that, so a bridle would be less effective, but I can't get my head around whether it would be an improvement on a single fixed point or whether the pulley would just slide right across to one side the moment that there was any steering input.

Thoughts please? There is any amount of stuff on towing bridles and any number of people trying to sell them, but nothing that really indicates how useful they are or what the optimum dimensions would be.
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Old 05 January 2015, 11:57   #2
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IMHO (and 25 years experience) there's nothing wrong with a properly sized rope bridle attached to good cleats or D-rings either side of the motor. Needs to sized right to allow the pulley to run freely round the motor, and the motor to tilt fully and not risk dropping past the anti-ventilation plate or getting entangled in the prop.
The main principal of these things is that they allow towing loads to align with the thrust of the motor, giving your much more predictable handling than a fixed bridle or towing off one side
Disadvantages Vs turboswing are that the tow rope is lower in the water therefore more succeptible to being sucked into your prop if going astern (simple solution - don't go astern when towing), and gives a bit less 'lift' if towing a skier. Conversely if towing heavy loads, bow will stay lower with a lower mounting point. Rope bridle / pulley will almost certainly result in a certain amount of chafe on your engine lower cowl / leg esp if you're running twin motors. Also clearly doesn't act as an engine 'nudge bar' like the turboswing does.
I guess it depends how much you want to pay for a few minor advantages over the tried and tested rope and pulley solution.
Alternatively approach a local stainless fabricator and see how much they want to fabricate something similar?
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Old 05 January 2015, 13:37   #3
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What do you intend to tow?
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Old 06 January 2015, 04:35   #4
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My only regular towing fixture is as safety boat on the annual New Year's Day raft race, which is why I don't want to spend 500+ on a Turboswing for one day a year. It's just a couple of hours of positioning and then recovery of various unseaworthy contraptions from the harbour, but some of them are quite heavy, it demands a reasonable amount of manoeuvrability with other boats and rafts on the water and towing off a cleat on a windy day you invariably find yourself at some point in a position where the cleat pull and the wind is acting in the same direction and you can't turn even with the steering hard over which in a situation with various other 'vessels' that are 'not really under command' can be interesting...

A thought I did have was to secure the tow line/pulley to the A frame with a very stretchy bungee, so as soon as the load came off it would haul clear of the prop. I guess I'd need to rig that up and see if it works or if it just pulls the rope in to the prop! I usually have somebody else on the boat to keep the rope clear anyway, so it's not a major concern.

If I can come up with something that works I'll carry it in one of the seat pods with the tow line so it can be clipped on easily if I ever need to use it.
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Old 06 January 2015, 05:08   #5
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On the sailing club Safety boats, we simply use standard 3 strand (12mm?) with plastic water hose over it (loosish fit) and plait an eye each end. The towline sllips along the plastic hose as needed. We find this works reasonably well for light towing duties. (we are towing dinghies and keel boats mostly and the odd RIB). If it was heavier than those, you would probably want something more substantial with a pulley.
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Old 06 January 2015, 05:53   #6
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Steven,

The “problem” you describe is faced by every dinghy sailing club across the world. Most adopt relatively simple solutions. A simple rope bridle makes a huge difference. Even without rigging an actual bridle you can help a lot by tying a short rope onto the main tow line and leading it to a cleat on the opposite side of the boat – this sharing the pull between both sides of the “tug”.

If you are worried about getting entangled in the prop then obviously make any bridle short enough to stop it going there – but some clubs add floats to the tug end of the float line (I’m sure some polystyrene packaging and improvisation could achieve the same thing for a “once a year” gig). It won’t completely prevent a cock up.

I’ve seen the “bungee to the afame” used once – not sure it was adding anything.

I’ve seen an old farmer use something a little like the stainless tow bar you referred to, essentially it was a rope bridle fed through a length of blue water pipe – the pipe seemed to go through holes in the transom (where towing eyes often are) and kept it up out the water.

A longer tow rope helps stop the towed boat from steering the tug. For very tight stuff towing alongside with the casualty vessel forward of your transom will help retain steerage.
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Old 06 January 2015, 06:33   #7
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The ski bridles that we used back in the day (still have one somewhere), used to have a plastic floating wheeled block. Simple, but effective.
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Old 06 January 2015, 06:34   #8
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Most of the time we don't bother with a bridle. With our lightweight sailing dinghies and short distances to tow — we only normally tow to get people in quickly when the wind disappears — it's not been a problem.

We do also have towing bridles. We made them out of quite thick rope — about 3/4" if memory serves — with a cork float. They have a fairly substantial snap hook on each end so they can be fitted as required. The tow lines are also attached to our end by a snap hook, so they can be unclipped from their normal place on the transom eye and clipped on to the bridle instead.

I suppose you could have a block on the bridle, like a mainsheet traveller, but personally I wouldn't add one unless I'd found out it was necessary, otherwise it's just another thing that can break.
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Old 06 January 2015, 07:32   #9
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Quote:
Originally Posted by Mollers View Post
The ski bridles that we used back in the day (still have one somewhere), used to have a plastic floating wheeled block. Simple, but effective.
I used to have something similar, until my eldest destroyed it with the snatch load of three of his mates on a towable
At the time I looked around for a pulley to rig onto my bridle but could not find anything that I was satisfied would withstand the abuse. Now have a simple S/S ring that slides along the bridle - not perfect but works after a fashion.
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Old 06 January 2015, 07:36   #10
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Bogmonster,
From the duties you're doing it definitely doesn't sound like it's worth spending lots of cash to solve the problem.
Suggested approach:-
  • Good strong rope bridle with either pulley or hose cover as suggested by others.
  • Some sort of float on the 'boat' end of the rope
  • Get your crew to manage the towline (if you're on safety duty you shouldn't be out without a crew). A bungy connecting the tow line to the a frame can help the crew to recover the tow line without having to lean over the back of the boat
  • If towing in open water, use a long tow (as long as practical given the circumstances)
  • If towing in confined spaces, tow alongside with the tow positioned well forward Vs the tug.

Have fun!
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