H16 trampoline double grommeted

oldgeezer

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Posted: Nov 06, 2021 - 02:57 PM

Completely replaced all old factory grommets on all three tramp pieces. Added new ones to double grommet
center of tramp. Also installed one each on the forward outboard corners. (About 110 nickel plated brass #4 grommets total. “Fun job”) My question is... what is the length of the lacing I will need now for the center. I can measure the rear ones. I will be getting all new line. Suggestions on line material/type is welcome. Thanks, Jim
waiex191

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Posted: Nov 07, 2021 - 09:37 AM

No replies yet, but I've got to ask - what is double grommeting?

I went with the lengths at Murrays.com and I think I used 1/4" braided line from Cajun rope.

--
Bryan in Poplar Grove, IL
Supercat 17, unknown year. Future project
Hobie 16, 1977 - died a spectacular death https://youtu.be/Y7O22bp2MVA
Hobie 16, 1978 - current boat
--
Dogboy

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Posted: Nov 07, 2021 - 08:04 PM

Double grommeting involves installing additional grommets for the trampoline lacings. Essentially, you add an extra grommet between each of the existing grommets along the center lacing of the tramp. This allows you to pull the tramp tighter and also help spread out the lacing load so there is less risk of pulling out a grommet. It is something that is generally only done on Hobie 14’s and 16’s where you want a very tight trampoline to help keep the frame rigid. You will end up using about twice as much lacing line as you would use on a standard tramp.

sm
charlescarlis

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Posted: Nov 08, 2021 - 08:31 AM

I don't know if it's common, but I liked using "Dyneema" single braid. Not because of strength, but because it's particularly slippery and pulls through multiple grommets easier. Seems to hold tension pretty good also. Just tried it because I got a deal on some red colored. Happy with it, except - don't buy red; it lasts about 2 weeks before it fades to pink for some reason.

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Chuck C
NACRA 500 Mk2
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oldgeezer

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Posted: Nov 08, 2021 - 11:46 AM

Dog boy:
Good explanation of double grommeting.

Charlescsrlis:
Thanks. Will look into Dyneema.
BigWhoop

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Posted: Nov 09, 2021 - 07:22 PM

I would use 3/16" or 1/8". They bend around the grommets better than the standard 1/4". They are plenty strong, the limiting factor is how you are going to tension them. Smaller line is harder on your hands. Garden gloves or one of those clam cleat things that windsurfers use to tension their lines. Dyneema is slippery but pricey for the amount you're going to need. At least try it out with cheapish hardware store line for the first year or so. Then you'll know how long to get the expensive stuff.

Another "double lacing" technique is to lace your trampoline. Then put in another line and tension that one. Now the first one will be soft. Tension it again. After the boat sits in the sun for a bit it will want this repeated.

Tight tramps make fast boats.
oldgeezer

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Posted: Jan 17, 2022 - 11:08 AM

Thanks to all your replies. I got som UHMwPE line on eBay. It’s the same family as Dyneema and Spectra. 100’ of3/16 (5 mm)diameter ,12 strand single core for $44 (free shipping) from ropeusa in Miami, Florida. Good price and made it the USA. Can’t tell the difference between it and Dyneema. Same strength and flexibility. UV protection. Since I added a grommet to each of the forward outboard corners,you’ll need about 70’ of line. I also turned the side rails around so the slots are aft. This line is the same as my Spectra jib halyard so I would use I for a replacement if needed. Worked out perfectly. Tramp is very tight now. To tighten, I made a 6” length of
1 1/2” pvc schedule 40 pipe. Cut a notch across one end (1/4” wide, 3/4” deep) and drilled a hole across the top end for a piece of 3/4x12” pvc for a twist handle. Secured it with tape. A rod or large phillips screw driver could work also. Filed edges of notches around the corners so they don’t damage line when tightening. Strapped across center of rails with a 2” wide ratchet strap to prebend them. Released after tightening lacing.
Jim
MN3

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Posted: Jan 17, 2022 - 12:56 PM

QuoteTight tramps make fast boats.

Wish i knew that when i owned my h16 - (i leared)
MN3

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Posted: Jan 17, 2022 - 01:04 PM

QuoteCan’t tell the difference between it and Dyneema. Same strength and flexibility. UV protection

chafe is a known issue with hm lines in this family - so keep an eye out, and simply reeving it again with a .5" change will reposition everything and extend the lines life once chafe starts to show

happy sailing!
MN3

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Posted: Jan 17, 2022 - 01:11 PM

QuoteI liked using "Dyneema" single braid. Not because of strength, but because it's particularly slippery and pulls through multiple grommets easier. Seems to hold tension pretty good also.

some newer HM lines come pre stretched (and cooked to seal in the stretch) but unless specified they all have some stretch (and a minuscule amount of creep). Esp when new. It's always a good idea to get the length you need PLUS enough for some knots that can be cut off without impacting the needed amount and tie one end to a tree, and the other attached to your mainsheet blocks (around another tree) and sheet in, get it good and tight and walk away and if possible - do it in direct sunlight and let it get worked. go back and sheet in again ... rince and repeat - now your tramp line will have most of it's stretch removed, and the creep in HM lines is minimal
oldgeezer

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Posted: Jan 17, 2022 - 01:32 PM

Thanks chief,
Planning on doing just that. Will watch for chafe. Does Dyneema chafe too?
Hopefully this line will hold up.
Jim
MN3

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Posted: Jan 18, 2022 - 08:24 AM

QuoteThanks chief,

That is Master Chief to you ;). (actually i was a Petty Officer when i served)

QuoteDoes Dyneema chafe too?

yes, most HM lines are known for it
that being said 5mm has 2800-5800 ish lbs of breaking strenght - your line could chafe, get super fuzzy and still have lots of life in it.

Edited by MN3 on Jan 18, 2022 - 08:26 AM.
texastuma

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Posted: Jan 18, 2022 - 09:31 AM

Typically you will not get chafe with grommets, unless they are done poorly; where there is an edge from the press. I would recommend checking each grommet before you install the tramp.

--
Scott

Prindle Fleet 2
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oldgeezer

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Posted: Jan 18, 2022 - 11:00 AM

Sorry Master Chief. Didn’t mean to insult you. I salute you. Appreciate the info. I wasn’t aware of that problem. With your knowledge of lines, I’m wondering if you are a Bosun’s Mate. I was in the Navy too. Now I’m a real sailor. ( Pun intended).
oldgeezer

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Posted: Jan 18, 2022 - 11:17 AM

texastuma
I installed them myself with a set tool and hole punch. If I saw an edge I would hammer it down till smooth before I went to the next one. All turned out good. Fun job. It’s laced up and tight. Will keep an eye on it. Thanks for the heads up.
Jim
MN3

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Posted: Jan 18, 2022 - 01:27 PM

oldgeezerwondering if you are a Bosun’s Mate. I was in the Navy too. Now I’m a real sailor. ( Pun intended).

when to captain's mast 1 time during a-school and ALMOST became a Bosun.
Thankfully, I didn't play with strings except on (uncommissioned) sailboats

I was a Mineman (hence the screen name Mn3)

"You sunk my battleship" is what i did for a day job. :)

Edited by MN3 on Jan 18, 2022 - 03:44 PM.
oldgeezer

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Posted: Jan 18, 2022 - 07:08 PM

MN3
You probably had more fun than me in that rate. I was a Tincan Sailor and Signalman on the USS Barry (DD933) . Four years was enough. Five hurricanes at sea. Became an electrician /control /instrument tech. Retired now. That means I’m still working but no pay.
MN3

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Posted: Jan 19, 2022 - 02:24 PM

QuoteThat means I’m still working but no pay.

lol

thanks for your service
oldgeezer

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Posted: Jan 19, 2022 - 03:22 PM

MN3
And yours also. Jim