vyv_cox
Well-Known Member
I seem to remember reading that too. Years ago I towed my Fortress anchor, 8 metres of 8 mm chain and 50 metres of anchorplait and was quite surprised to see the anchor breaking the surface occasionally.
50M of warp as a drogue?
- Thread starter pcatterall
- Start date
I seem to remember reading that too. Years ago I towed my Fortress anchor, 8 metres of 8 mm chain and 50 metres of anchorplait and was quite surprised to see the anchor breaking the surface occasionally.
prv
Well-Known Member
Indeed. Or my mate who neglected to mention that he didn't have his contacts in and couldn't really see anything more than a few yards from the boat...
Pete
PuffTheMagicDragon
Well-Known Member
The instruction should be "Keep pointing at him!" If they do this, even if they momentarily lose sight of the head behind a wave they will still be pointing close enough to where the head will reappear.
TQA
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Bernard Moitessier wrote about towing stuff in survival storms in his book Cape Horn: The Logical Route.
I recommend anyone considering towing warps in storms read it.
I recommend anyone considering towing warps in storms read it.
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But I seem to remember he decided to cut them and rely on speed to outrun the waves at some point. I may be wrong, I don't have a copy to check.
I also remember a couple of lads who sailed the Atlantic in a catamaran. They very successfully used as a rogue...their Seagull outboard!
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Were the shock loads severe, or did the length of the rope reduce them? I guess shock loads would be a big problem.
thinwater
Well-Known Member
The shock load cannot exceed the drag of the warp. It is not an anchor and does not have mass.
One advantage of a warp is that you do not need to cut it. Release one end and winch it in. You may need it later!
One advantage of a warp is that you do not need to cut it. Release one end and winch it in. You may need it later!
vyv_cox
Well-Known Member
It wasn't done in severe conditions. There was considerable drag but no shocks that I remember (but it was more than 25 years ago!)
macd
Well-Known Member
That's my recollection, too. In fact didn't he also jettison a copious quantity of lines and spares to reduce weight?
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The warp still has mass, surely. If the stern of the yacht is going up rapidly on a huge wave, while the warp is being dragged down into a trough, there will then be shock loads exceeding the mass of the warp, surely?
PuffTheMagicDragon
Well-Known Member
More than the mass I would say that it is the friction between the rope and the water that affects the drag. There would not be shock loads because the varying up or down of the drag would be gradual, being a function of the speed through the water.
This is unlike the shock loads that present themselves through snatching when lying to an anchor.
GHA
Well-Known Member
With the other forces involved and the very low mass of the rode any additional forces due to accelerating the mass of the rode will be negligible, still there but maybe not even possible to measure in the real world.
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OK, makes sense, as does Puff's post. So stern mooring cleats should be more than strong enough to stream warps from.
PuffTheMagicDragon
Well-Known Member
"Should" is the operative word here.
Please do not take anything for granted because I have seen what appear to be substantial mooring cleats torn out of the flimsy deck of new boats (Famous European builder who I shall not name).
For your own peace of mind, take a good look under the deck and check for yourself what there is holding the cleats in place; if necessary beef up the GRP over a larger area and install large pads instead of the usual penny washers.
bitbaltic
Well-Known Member
You'd also expect the friction to increase as a function of boat speed, which is why experimenting with streaming warps in calm conditions might be ineffective unless you test them out by motoring. Perhaps it's possible to map boat speed against revs motoring with warps in flat water and extrapolate to survival conditions.
I've read lots of accounts of survival tactics but never recall one where a survivor witnessed warps pull the attachment points out of the boat. Perhaps this suggests that if this does happen, one does not survive. I for one would not be too concerned about damage done if I'd both felt it necessary to deploy warps and lived to tell a tale about it, but we are a cruising boat and would expect never to be in that position. I keep meaning to buy a drogue (specced up a competent bridle years ago) in the meantime I comfort myself that the dinghy lives in a huge builders' bag.
Poignard
Well-Known Member
I have a 48m Octoplait kedge warp that I could use. I suppose it would offer more friction than a braided rope.
PuffTheMagicDragon
Well-Known Member
I should think so because the braided rope would be virtually smooth in comparison. Diameter for diameter, the Octoplait has more - and rougher - surface area exposed to the flow of water, due to its construction.
thinwater
Well-Known Member
Roughly the square of boat speed.
pcatterall
Well-Known Member
Sorry I am lost now. Can you explain this please? ( what is roughly the square of the boat speed?)
lw395
Well-Known Member
Have you ever towed a warp?
Even towing a shore line (20m? 25m?) in nearly flat calm, the drag was significant.
As it picked up to sailing breeze with 'slight' sea condition, the drag got a lot more.
(This was to clean the rope after it got dirty in a fishing port.)
Any waves and you will be dragging bights of the warp through the waves as they try to make the rope follow their shape.
I think the drag from a long warp could be quite high in rough water.
Hard to put numbers to it though.