Boom / Mast Prep and Paint

[The Froon]

I am in the process of restoring the boom and mast of Froonie, and have some general questions:

1. In the process of removing the rivets securing the cheek blocks, I accidentally got a little aggressive on one the holes - opening the edge up just a bit. Would it be wise to fill all four holes now and relocate cheek block? The damage to the original hole is pretty minor, so my thinking is that the next rivet should not have an issue, plus there are three others securing the block.

2. If I did choose to relocate the cheek block, I understand that expoxy can be used to fill the holes. Given the boom is hollow, how is sufficient epoxy built up to properly and permenantly fill the hole?

3. I do not hae expeirence with a spray gun, nor the funds to secure one, so is brush-on technique suitable for anti-corrosion primer and finish paint? I plan to roll and tip.

Thanks,

Brian

[Rich P]

With regards to the rivet issue, I work as an Aircraft Fitter, so we put a few in!
If it was a solid rivet then you wouldn't have a problem, but blind 'snap' rivets don't fill the hole in the true sense of the word, if the damage is as you say minor and the rivets aren't under high load then you should be ok. A shear load shouldn't be a major problem, but if the load is trying to 'pull' the rivets out, than I would recommend filling the holes.

Blind rivets can be tricky to drill out because you get so far and then they start spinning in the hole, which doesn't do it much good!

[Tim]

Instead of using new rivets, why not drill and tap the holes for machine screws? You might well be able to use the same holes, or else slightly relocate the piece, fill the old holes, and redrill.

Epoxy will fill the holes just fine. Use a countersink to ream the top of the hole for a wider bearing surface.

You can hand-apply all the products you might need to use for repainting.

[LazyGuy]

When I re-did the mast for the Sea Sprite, I drill and tapped the holes. It worked out very well. Particularly with me, I never do everything I want to do the first time so I end up going back and re-doing portions. Reoing threaded fasteners was much easier than drilling out rivets. If you decide to tap the holes, get the next larger size (I had a 12-32 and 14-32). That way when if I messed up the 12, and I didn't want to go through fill the hole, sand, repaint etc... I just ran the 14-32.

I did my mast roll and tip but I only needed to spot prime and I used brightsides (I no longer use brightsides om my boats except maybe for the interior.

[The Froon]

All great suggestions, thanks! I familiarized myself with the drill and tap process today...this
is how I will proceed. What is the easiest way to measure current hole size and corresponding tap to use - going with the next larger size?

Thanks forum,

Brian

PS - Tim, I read that you used Awlgrip for Glissando's mast...are you now not advocating Awlgrip? I thought I read recently that you were unhappy with Awlgrip...

[Rich P]

A rule across the hole is the simplest way, or you can use the trusty pushing drill bits in till you find the correct one.
The correct pre-tapping drill size can be found in a set of Zeus Engineering Tables, or I imagine there will be a resource online that lists as well!

[One Way David]

In most cases you'd be looking for a specific sized tap. Here I'd recommend using a drill bit to size the hole. Use the non fluted end to push into the hole. It should go into the hole using finger force, and not much of that. Much easier than measuring unless your a machinist, but then you wouldn't be asking these questions. Go to a hardware store and look at the tap sizes. Most of todays taps will have the drill size required stamped or otherwise marked on them. Select the next size larger, or whatever you want. Almost always the drill size will be an uncommon one, ie. not in the usual home/boat owner's inventory. So on your next trip to the store get the appropriate drill bit (Well, that's the way I shop!). Also, if everything on the boat is metric, do this in American or vice versa. It just makes it more interesting for the next owner;)

[Tim]

PS - Tim, I read that you used Awlgrip for Glissando's mast...are you now not advocating Awlgrip? I thought I read recently that you were unhappy with Awlgrip...

No, not at all. Awlgrip was and is a great product line.

I switched to Alexseal 5 years ago because of a supplier issue, not because I think the product is necessarily better.

[Drew]

I suggest sizing the new threaded fastener and corresponding hole based on the mounting hole in the hardware you are mounting rather than the existing holes in the boom. Choose a fastener that will comfortably fit the hardware and get the appropriate tap and tap drill for that fastener. Do measure the hole though, just to be sure it is smaller than the tap drill size. It an be easily measured with calipers or approximated by using drill bits as gauge pins.

Drew

[The Froon]

Thanks Drew; sound advice, as the fair leads and ckeek blcks are in usable condition - no point in scrapping the usable stuff...restoration expenses add up quickly.