Fixing a cleat to a polythene (Funyak) tender

Praxinoscope

Praxinoscope

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I have a dislike of self tapping screws high seem to be the standard way of fixing attachments to polythene boats, in fact I try to avoid using self tappers on anything, specially GRP.
As these boats are double skin the normal machine screw with a pad backing just isn' t feasible.
I was thinking of using a couple of rivnuts but I'm not sure this option will work
Has anyone fitted a cleat or some other item to a boat of this type?
 
There are a sort of rivnut made of rubber with a threaded metal insert to squeeze the rubber and grip in a blind hole; as long as the polythene was fairly thick they might work. If it needs to be more secure then attaching the cleat to a metal spreader plate and use multiple self-tappers to hold the plate on?
 
The boats are made from Polyethylene (aka PE or HDPE or possibly MDPE). Definitely not Polythene. However, CT! is not recommended for PE.
 
If you can screw it onto a larger plastic plate with countersunk screws there is more chance of it staying put when glued. At work we have been using various Permabond adhesives for plastics but not for PE.
Some information here:PE bonding. It doesn't look easy.
 
Aeolus said:
The boats are made from Polyethylene (aka PE or HDPE or possibly MDPE). Definitely not Polythene. However, CT! is not recommended for PE.
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James_Calvert said:
When I was a boy I was told that polythene is polyethylene.

The former was a trade name.
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Polythene , polyethylene or polyethene ........ all the same thing.. A polymer of ethylene, preferred chemical name ethene
 
VicS said:
Polythene , polyethylene or polyethene ........ all the same thing.. A polymer of ethylene, preferred chemical name ethene
Click to expand...
Cambridge dictionary.

polyethylene
noun
(also mainly UK polythene)


a light, usually thin, soft plastic, often used for making bags or for keeping things dry or fresh:

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To the OP: I doubt anything can transfer much load to the PE without cracking over time., so a choice between poor options. A rivnut is probably on of the worst. Toggles would work.
 
Aeolus said:
The boats are made from Polyethylene (aka PE or HDPE or possibly MDPE). Definitely not Polythene.
Click to expand...
Same stuff. Ethylene is the old name for ethene (just as actylene in the old name for ethyne).

Is a FunYak like a SportYak? I have one of those and would only attach thing by bolting through the "rim".
 
The other thing is, how old is this Yak?
It's possible to get new PE welded.
Old UV-aged PE is more difficult AIUI.
OTOH ,some glues and sealants will stick to aged PE.

How strong does ths cleat need to be?
How thick is the plastic?

One method is to cut a slot, slide in a metal plate with tapped holes and clamp the plastic between two pieces of metal with oodles of sealant.
 
Thanks for all the suggestions, the cleat should not take a great deal of force as its primarily intended to keep the pick- up line in place when tender (a Fun Yak Telline about 4 years old) is left on the mooring.
CT-1 certainly wion't hold on to polyethylene or whatever one wants to call it,
I want to fit it on the forward gunnel, so well clear of water line, I have seen them fixed on with self tappers, but I just don't like using them, that's why I wondered about rivnuts.
I have done rough repairs on 'poly' boats before using a strong adhesive in a hot glue gun, but not sure this is suitable for my cleat option.
Will let you all know as and when I'm successful.
 
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