PDQ 32, length of tramp lacing and diameter

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PDQ 32, length of tramp lacing and diameter

Postby thinwater » Tue Jan 24, 2012 3:08 pm

Since there is about 22 feet of join (if we double count the center as it is double laced), I'm figuring 45 feet of 3/8-inch, allowing for knots.

Does any one know? One owner posted 20 feet, which is clearly too little, and I saw nothing in the manual.
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Re: PDQ 32, length of tramp lacing and diameter

Postby mikeandrebecca » Tue Jan 24, 2012 5:35 pm

I recently replaced it with a length of 3/8 line that I had handy. It was 70 long when I started and I had approx. 20 feet left over. Approximately!

:)

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Re: PDQ 32, length of tramp lacing and diameter

Postby mikeandrebecca » Tue Jan 24, 2012 5:40 pm


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Re: PDQ 32, length of tramp lacing and diameter

Postby thinwater » Tue Jan 24, 2012 7:00 pm

And where did you stand to work? I re-laced my Stiletto tramp (practically identical) 3-4 times, but I was either on-the-hard or in shin-deep water. I did take it off one time at the dock--falling in would have been easy. I've thought of laying a ladder across the gap.

Thanks for the help. I just noticed today that mine are getting a bit scary. I did replace my jacklines, so as long as I'm clipped in, I guess I'll just get towed.... until I hit shore if I'm single handing! Of course, given the 34F water temperature, that won't matter much to me by then.
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Re: PDQ 32, length of tramp lacing and diameter

Postby thinwater » Wed Jan 25, 2012 5:37 pm

... and how about Amsteel for lacing? It seems about the same price as polyester yacht braid on an equal-strength basis, won't stretch, and should be easier to lace, being slippery and smaller in diameter. I'm thinking 1/4-inch would last forever, though I could go 3/16-inch.

How have your Amsteel lifelines held up in the sun? They were beautiful when I saw them in Cape May. I'm thinking I will do the same in just a few more years.
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Re: PDQ 32, length of tramp lacing and diameter

Postby mikeandrebecca » Wed Jan 25, 2012 6:54 pm

That's funny that you ask about the lifelines. I am just writing about that for tomorrow's blog post. Stand by. :)

As for where we stood while re-lacing the tramp, we stood on it. We started at the aft, center position. As we removed a few criss-crosses of the old line, we added the new line in it's place, working progressively until it was all done. Only a few grommets were ever undone at one time. To finish off the ends we had the dinghy in the water and stood in it to tie knots underneath at the port and starboard bows.

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Re: PDQ 32, length of tramp lacing and diameter

Postby mikeandrebecca » Wed Jan 25, 2012 6:55 pm

And yes, I think Amsteel would rock for that application

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Re: PDQ 32, length of tramp lacing and diameter

Postby thinwater » Wed Jan 25, 2012 8:00 pm

It never occurred to me to lace a little at a time. THAT was obvious!

1/4-inch Amsteel it is.

Thanks, though you may have cheated the world of a photograph of me getting wet in February!
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Re: PDQ 32, length of tramp lacing and diameter

Postby mikeandrebecca » Thu Jan 26, 2012 5:59 am

:)

Here is my report after almost 2 years with the Amsteel lifelines:

http://www.zerotocruising.com/battling-our-arch-enemies-rust-and-chafe/

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Re: PDQ 32, length of tramp lacing and diameter

Postby Iriemon » Wed Sep 20, 2017 2:36 pm

About a year ago, I bought new tramps (through Sunrise -- happy) for my 32, and debated what to lace them up with. After looking around a bit, it seems like most tie their tramps up with a non-stretch line (like sta-set). However, I wanted something with some stretch to it, because, in my observations, tramps tied with non-stretch line tend to be floppy and saggy, and don't have much "give" to them. After consideration, I chose 1/4 inch twisted nylon.

I have to say, I do like the results. The nets stay nice and taut, and don't flop or flutter in a breeze. There is also a nice "give" to the tramps when people get on them that makes them more comfortable and "trampoline-like.".

However, the nagging issue is safety. 1/4" twisted nylon has a minimum breaking strength of around 1500 lbs. Sta-set is about 2000 lbs, while Amsteel is claimed at 7700(!).

Now, the easiest answer is to use the strongest rope you can find. I could put 1" Amsteel on it and feel pretty safe. But there is such a thing as overkill, and like I said, I want a little stretch, if possible. Neither Amsteel nor sta-set have much in the way of stretch characteristic.

Over the past year, I've had some hefty folks on the nets. I'm not sure I've loaded it with 1500lbs of people, but I'm sure I've had at least 1000. After a year, the line still looks good. No signs of fraying or stress. But still, I have some nagging doubts, so I decided to put it to the board.

My first question is whether the lacing of the tramps enhances the rope strength. I would think so; that a laced rope has stronger breaking strength than a single line of rope. Maybe our engineering friends can answer that. If the lacing increases the line's breaking strength, I'd feel more comfortable.

My next question would be for rope wizzes who can identify whether (other than breaking strength) twisted nylon would be particularly ill-suited for lacing tramps, compared to braided.

And finally, whether anyone thinks this is a particular bad idea for any other reason.

Because the two tramp sections on the PDQ are secured on two sides by slotted guides, the biggest danger of a sudden line failure would be slipping in between the two halves. I'm thinking I could tie in a couple strategically placed pieces of Amsteel to serve as a backup for that contingency.

Thoughts and comments appreciated. Thanks!

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Re: PDQ 32, length of tramp lacing and diameter

Postby thinwater » Wed Sep 20, 2017 4:52 pm

Yes, the lacing works as a lashing, so the strength will be BS x number of lacings in relevant area x wear factor x bend factor.

If if the weight is in the enter, most of the lashings in the center are loaded (>10) and the strength is great. The worst case is a bounce near the edge where the load could be split between the tramp and a few lacings. So the stress should never be more than about 1/4 on any lace.

Rope weakens with time. Rope loses strength in bends and knots. Figure about 10% of BS as working load. So the SWL of 1/4" nylon, as a lacing, is about 600 pounds in a small area. I doubt you will excede that. You will need to re-lace ~ 5 years.

I've used 7mm polyester and 1/4" polyester. I would not used laid rope--I think it would be hard to tension, though it would work.

It is always good practice to secure the lacing at regular intervals (see World Sailing Off-shore Regulations). However, this can be a knot or a lashing between laces. It should NOT be a low stretch material or it will locally overstress the grommets (it will carry the load).
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Re: PDQ 32, length of tramp lacing and diameter

Postby Iriemon » Thu Sep 21, 2017 5:27 pm

Thanks Drew, very helpful.

Bryan


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