Hey All,

I'd like to rivet two fairleads (rotation and cunningham) to the deck of my Taipan just in front of the chain plates and a small cam cleat (jib sheet for superslooping) just behind.The fairleads won't need to bare much tension but the cam cleats will.Should I cut an inspection port into my hull first (probably just behind the front cross beam) and screw the hardware into a backing piece of plastic or can I just pop rivet through the deck and be unconcerned about the decks ability to hold the loads ?

Has anyone got a picture of a cam cleat attached at the shroud adjuster (saw this a while back on this site) ?

Oh, and while i've got ya - to match luff curve of a new main to your superwing mast would you START by changing the spreader rake to match the new sail or would you sail with old calibrations , look at the sail trim and then start the recalibration process ?

Thank You !


Paul

I would think that riveted with an epoxy base would work well without having to cut an inspection port.

Would it be possible to run a small shackle off the chainplate with your block attached to the new shackle?Basically, put a longer "pin" in where the chainplate and shroud adjuster connect, add a shackle there and add the block.

This may not be the most elegant solution, but may be the simplest and no new holes in the deck.

PTP - thanks.

Tom - I've got a turning block to gennaker clew already attached to the chainplate and have learned not to have more than one line converge near any block because they tend to jam the block...Congrats on the Blade (i hear they're crazy fast and Marstrom build quality...) ! Look forward to seeing you at the next F16 National champs (2007 Houston ?)...

PK

Paul,
Below is the general approach I would consider.
First I would put some packing tape over the deck area where you are going to locate the fitting. This is to protect the deck and negate the need to clean resin off the deck.
Please also note that due to the viscosity of the resin it is not always easy to fill a small hole with resin.
You will think it is filled but usually ends up with an air bubble in it that can be most of the void you are trying to fill. The smaller the dia hole the harder it is to completely fill.
Basically I would consider drilling a 1mm hole through both skins and a hole larger than the dia needed for the rivet in the outside skin but not through the inside skin. The 1mm hole left through the inner skin is to ensure air can get out as the resin in injected but small enough to retain the resin thickened and strengthened with micofibe blend or milled fibres. The larger outer hole will help when trying to scrape out as much foam as possilbe to increase the area the resin can bond to and better distribute the load. I'd probably scrape clean the top of the inner skin under the outer hole and use a vacuum to extract foam debri to ensure the resin bonds to the laminate and not to stray bits of core.
When you mix in the microfibre blend or milled fibres with the resin make it not too thick and not too thin and you really should inject the resin into the hole with a siringe.
If you try to put it in by other methods you will most likely end up with a bit of resin on top and a lot of air benieth. I've leave the resin slightly proud of the deck and trim with a razor blade once cured but still green. Then remove the packing tape.
Last I would probably not rivet but screw into the resin insert I'd made in the deck.
This is just the way I'd approach the same issue if it was my boat.
Hope this helps.
Regards,
Phill

Simple way of ensuring a good resin filled base to any rivet in a foam hull is do the following
bend a small nail with about a 5 mm 90 degree bend
drill the rivet or screw size hole through just one skin
put the nail into a small drill
push the 5mm bend of the nail through the drilled hole
give it a whirl with the drill ( you now have a 10mm void made in the foam )
if you want a bigger strengthened area simply put a bent nail with a longer bend on it and give it another whirl. Take small chunks at a time or you could run the risk of damaging the lower skin.
Fill the void with resin and filler ( not micro balloons)
Let the resin set and then drill the correct hole size through both skins. If you are in a hurry you can use one of the fast setting " Araldite " dispensors mixed in with a bit of filler as it sets in about 20 minutes.

Phil, have you ever tried (in addition to the technique you described) attatching an approx 50cc syringe to the drain plug hole(ie, using a hypodermic needle through a cork) and applying a little bit of negative pressure on the hull to draw in the epoxy and evacuate the internal bubble? You wouldn't want to be too agressive and you'd need to get the viscocity right or you'd suck some epoxy into the inner hull...

Have you ever used threaded inserts into epoxy? These are really interesting; they require slightly larger holes but provide a much stronger attachment and the screw can be inserted and removed without degrading the strength as I think might occur with a screw into an epoxy hole. I think some inserts can be epoxied in place without having to tap. I don't know if it would be possible to tap an epoxy hole and even if you could you'd still need to apply a thin coat of epoxy or adhesive silicone prior to installing the insert. Just food for thought.

In general, when do you epoxy a hole for a fastener vs put in a backing plate or SS washer?

Jerry

Wayne,
Good trick with the nail to break up foam for removal but
personally I would still inject the resin.

Jerry,
I could always pull a light vacuum as you have described but never tried it and given the hull volume a siringe may not be enough. Usually the positive pressure from the siringe is enough.
When I was building my house I set thread into epoxy to attach cantilevered verandahs that I designed to the side of the house. It worked well but I have not seen them small enough for boat fittings.

Phill

Thank You for taking the time to help me out !!!


Paul

Phil,

The techniques described above are essentially the West System (Gougeon Bros.) recommended ways to secure fittings to foam core surfaces. Never use pop-rivets in such surfaces if you want to hold any kind of loading. A rivet requires very high compression against the rivet head and pulled section. This kind of compression cannot be achieved against cored composites and even just the laminate skin.

One tip I will add to the techniques described above...place the screws into the un-cured epoxy. Just spray them with WD-40 or cooking oil/PAM to allow them to release later on. This makes a very nice threaded section in the epoxy for maximum strength.

Mike.