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  #81  
Old 07-22-2011
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Towing a inflatable for me was always an indication that I was less inclined to do what I should and was willing to take the chance of messing something up while sailing. I've tried every towing opption suggested here and I think on deck or deflated is still the best choice.
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  #82  
Old 07-22-2011
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jmayton You might be right but I stil haven't seen a easy quick solution for getting (and storing) a 14' inflatable with wood floor and 160 plus pounds of engine out of the water without hurting the S/V or the dink. Therefore just tow it with a slide bridle and live with the 1 knt less speed.
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  #83  
Old 07-22-2011
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understanding

One of the joys of sailing is discovering your limits; some are dictated by the boat, gear, weather, knowledge, or physical ability. The elegance of our work arounds or jury rigs is what makes us salty.
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  #84  
Old 08-28-2011
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Originally Posted by sailingfool View Post
No need for a bridle at the boat end. Two points to make.

Add a third line from the dingy bow handle/tow attachment ring to the bridle. Adjust this line so it is just long enough to take up the force of a pull directly ahead. It will then also take up any non-horizontal pull. A problem with the bridle lines to the side D rings is that if you tow the dingy through rough wave action for a day or so, the bridle lines will rip the fabric tabs holding the D rings right off the inflatable tubes - these ring attachments are not designed to take loads off the horizontal. A short center line ensures the only pull on the side D rings is generally horizontal, whether to left or right, but not up/down.

The second is to run the dingy tow line to a secondary winch, if you have one. You can then easily adjust the length of the tow line if necessary even when underway. You should shorten the line whenever you anticipate manovering or stopping, such as when entering a harbor.
Sailingfool, I respectively have to disagree with your analysis. The D-rings are held on with adhesive patches. I'm assuming no additional sticthing. The patches will hold the most force when they are loaded in shear as opposed to tension. Shear loads are the loads parallel to the adhesive surface. It doesn't matter if the shear load is horizontal w.r.t. to the water or vertical. The strength will be the same.

The reason for a bridle, with the tow line fixed at the center of the bridle, is to cause the dingy to straighten when it turns to one side or the other. Let's say the dingy turns to starboard. The starboard half of the bridle takes more load and it is reduced on the port side. When this happens the larger load, on the starboard side, becomes even more closer to pure shear.

When the dingy goes up and down in waves, the load remains a shear load.

By adding another line, in your case from the bow handle to the center of the bridle, you are simply distributing the load between more points. This reduces the stress on the D-ring attachments. That will reduce the chance of failure in rough weather, but it is does not have anything to do with non-horizontal forces.

Aside from wanting to use the bridle to help keep the dingy tracking straight, there is another reason to use it. Attaching a tow line to the handle or bow D-ring puts that patch in pure tension. That's the worse thing you can do. I suspect that most handles and bow rings are attached with stitching as well as adhesive to take into account the high tensile loads here. But maybe not; I haven't looked closely.

In short, failures of the D-rings in rough seas is purely due to the fact that they are "rough seas".

It's interesting to note that if the D-rings on the bow sides are meant for towing, then they are not installed in the optimum direction. The standard is for the straight part of the "D" to be horizontal. It should be vertical for the purpose of towing. This will allow the D-rings to lie near flat when towing. This helps ensure shear as opposed to tension.

I've towed a dingy with a bridle and hauled it with the dingy bow on the stern of the boat. I prefer davits!

Happy sailing.
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Oops.

Oops. "Dinghy" not "dingy". Though I see a lot of dingy dinghies.
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Old 08-31-2011
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I only tow the dinghy when I am not travelling but make short jumps on the cruising ground (less than 30nm) and with time and experience I have come to some conclusions:

1-never tow the dinghy with the engine or oars inside. It makes it a lot slower and in the eventual situation of strong winds you can get a capsized dinghy and lost oars or damage the engine (happened several times including this year, I mean capsizing the dinghy).

2- pull it really close to the boat and use some system that can provide a lift of the dinghy bow. That will give significant less drag.

I don't like to use the back-stay for that and use a system that provides an attenuation of efforts (kind of suspension) and the distribution of efforts by several parts of the boat. Main effort (horizontal pull) is on some strong part of the boat, the lifting pull is on the back life lines (not much force).

Regarding the dinghy I distribute efforts by the two lateral D rings and normally pass a security line on the one in the middle, just in case.

Because the bridle (bowline knot) is big most of the force is forward and as the dingy is keep near the boat and pulled up, even with waves, the lateral pulls are very rare and not strong.

With this system you only lose about half a knot speed, about the same you lose with a fixed propeller to a feather one.





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Paulo
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Old 09-26-2011
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Originally Posted by SpawnyWhippet View Post
I respectfully suggest you think about that for a second. How can towing something not slow you down?? And if there was so little stress on the dinghy, how is it that so many are lost or discovered floating at sea minus their D-rings? I personally have lost one and my father alone has found 2 at sea in the last 5 years.
My boat cruises at 7-8 knots; when I have to tow the dinghy it's more like 6-7 knots and there is no way I can pull the dinghy towards the boat by hand at that speed.
I respectfully suggest you read what I wrote and try it. My airfloor inflatable is 10'2" long and it has a 9.8 Hp motor. I tow it at 6.5-7 knots. I can hold the tow line between my forefinger and thumb. If I pay out another 6-10 feet of tow line, I can barely hold on with two hands. Try it, and you'll see what I meant when I suggested there are some dim bulbs losing dinghies for no reason.
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Whether sailing or motoring, your displacement hull pushes a lot of water and much of it is piled into a mound behind the boat. That is the wake. That wake follows us whether we tow our dinghy, or stow it on deck. Like all mounds, it's easier to go down them than up them. That's why ski resorts have chairlifts to take us up, and skis to slide down. If you position the dinghy so it skis downhill, it gets a free ride. If you position it so your boat becomes a chairlift and constantly drags it uphill, then you lose boat speed and perhaps the D-Rings pop off. Why people struggle with this obvious concept is beyond me. It works--I do it every week.
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Old 09-27-2011
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short towing the best

Aasem I agree that you shouldn't loose a dinghy if made fast right and from my experience the best tow-length is riding "off" your own boat wake as close as possible to one or the other side of the transom, but never in the center as explained by 'Aasem'. Longer lines give a chance for 'dirty' water to throw the dinghy of the S/V's wake (I speak from experience, tried it both ways)
I'm always able to direct hand pull my dinghy closer to the aft of the boat without resorting to a winch and that is over 350lbs of dinghy. (finger & thumb is questionable, hand yes)
I disagree that it doesn't really cause any friction riding down the wake, it will still slow me down by more than 1 knt.
We'll find out again this weekend with strong winds (25mph) when pulling her for 20 miles.
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Old 09-27-2011
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Quote:
Originally Posted by Aasem View Post
Whether sailing or motoring, your displacement hull pushes a lot of water and much of it is piled into a mound behind the boat. That is the wake. That wake follows us whether we tow our dinghy, or stow it on deck. Like all mounds, it's easier to go down them than up them. That's why ski resorts have chairlifts to take us up, and skis to slide down. If you position the dinghy so it skis downhill, it gets a free ride. If you position it so your boat becomes a chairlift and constantly drags it uphill, then you lose boat speed and perhaps the D-Rings pop off. Why people struggle with this obvious concept is beyond me. It works--I do it every week.

Towed dinks can be adjusted to the hull speed and stern wave to reduce drag but ti still does not eliminate it. The stern wave moves a lot depending upon your hull speed so we adjust the painter length many times per day when towing. When it's surfing the stern wave there is a drastically reduced drag & load on the dinghy and your vessel but not eliminated.

This only works well however in calmer seas and in following seas the dink can surf up and bump your stern requiring a longer painter length. In slightly rough weather, when already sailing at hull speed down wind, I will often deploy the dinks beach wheels (Pellican wheels) which creates a sea brake like action and stops it from surfing & yawing. It also keeps it from snatching when it surfs and gets sideways. We regularly tow ours in up to 20-25 knots and have never lost a dinghy (40 years of myself and family towing dinghies). Above that it goes on deck. In real light winds it goes in the davits to make the best speed we can. We tow with a single point attachment to the bow ring of the RIB. If we had just an inflatable we'd two with the two d-rings but our fiberglass hull is far stronger than our hypalon glued on d-rings.
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Last edited by Maine Sail; 09-27-2011 at 09:17 AM.
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