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-   -   Pile Mooring - Mooring Line Stretch? (http://www.sailnet.com/forums/gear-maintenance/44066-pile-mooring-mooring-line-stretch.html)

lrak 06-11-2008 06:50 PM

Pile Mooring - Mooring Line Stretch?
 
Greetings all...

I need some expert advise on what seems to be a simple issue but drives me nuts :)

My baby - a 25 foot tophat - is on pile moorings in an area that has strong currents - up to about 4 knots.

The issue I face is that the distance between the pile is about 16 metres and the boat is only 7.7... so there is about 4 metres of line out from both the bow and the stern.

The rings on the pile itself mooring line is about a 1 metre above the highest tide and about 2 metres above the lowest tide...

Ok, sorry to ramble - just trying to paint a picture.

When I first moored there the person before me advised that I should tie off loosely so that the boat would drift a distance of about it's beam on the change of the tide... the mooring is not perfectly in line with the piles... but this means that at high tide the lines are in the water and getting algae growth etc. The algae annoys me and also the fact that my boat moves around so much...

Looking at the other boats does not really give me a good idea as they are all much larger and on level with the mooring piles... but they do not have lines in the water at high tide and taut lines at all time.

Heres the question :) Should I be tying off tight, or near tight, and trusting that the lines I use will have enough stretch in them to absorb the movement during the tide? Given there is basically 8 metres of line out to absord 2 - 3 metres of movement can I expect to get this from the nylon line with out ripping out deck fittings? I am too scared to tie off tight at this stage as I have visions of breaking something.

Any help greatly apprecaited.

Thanks

Karl

sailingfool 06-11-2008 10:21 PM

Absolutely tie the lines long enough to allow for the fall in tide without inducing material strain on the lines or attachment points. This document has some info on the stretch characteristics of nylon, http://www.mazzellalifting.com/catal...ad/cordage.pdf, which is longer than I thought! But if you secure your lines so the boat hangs on the lines, at all, you are engaging in an expereiment to find out where is the weakest link, and you are likely toi find out the hard way.
Secure the bow and stern lines to the nearest piling a little shorter than the distance between pilings (i.e. the boat can't reach a piling on either side. then add a bow spring line and a stern spring line each long enough to hold the boat in the center, they don't need much slack due to their length and angle. The boat should pretty well stay in place, be glad you arn't in Maine dealing with 12' tide drops.

mallo 06-12-2008 07:59 AM

I would suggest that the lines would be tight enough to keep the position of the boat but not so tight you are causing damage to the fittings,
This brings back a memory we were moored up to a string of floating moorings and wanting to leave at high water to find the knot tied to the buoy about 10ft under water, after a lot of winching, (sheet winches fed through the fairlead) we managed to pull the knot up to the sea level and put another rope on it and untie it. We had to do the same on the bow using the anchor winch!!
But that’s to be expected with 40ft rise and fall……..
Try and experiment with having them tighter or looser and see how you get on, I would suggest every situation is different.
Good luck
Michael


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