Friday, August 24, 2007

Float hatches attached

I finished attaching my float hatches today. My goal was to get both floats buttoned up tight, so that I don't get too many animals or insects in them while they sit in the backyard. Recalling my previous near-disaster with the expansion of a heated, enclosed float, I decided to make doing the transom vent holes the first priority.

The transom is one area where it's basically impossible to use machine screws, so I settled for sheet metal screws, attached through a core of high-density epoxy mix. Here's what the starboard looked like, before attaching the cover:

The hole in the middle is obviously the air vent itself; Ian specifies a 2mm hole. I found the suggested SeaDog vent cover to be extremely flimsy and went instead with a Perko model, much more sturdier and nicer looking too IMO:

Attaching the hatches was more tedious than I expected. Obviously you have to drill holes; I did this by first drilling small pilot holes with the hatch in place:

Then drilling the final holes with the hatch removed:

I had been concerned about the putty fill extending deep enough to surround the screw holes but this wasn't a problem; it appears I was pretty aggressive in digging out the core for edge-filling, and each hole appeared to be solidly drilled through epoxy.

Silicon was the hatch-makers' recommended sealant, and although other alternatives exist (3m 4200\5200, LifeSeal, etc) I decided to stick with silicon to make it easy to remove the hatches in future. It was pointed out to me (thanks Henny) that silicon can make future paint jobs quite difficult - hopefully I don't come to regret this.

My procedure was to lay down the silicon bead around the underside of the hatch flange, then lay the hatch in its float hole, push the screws down through each hole, press the hatch down lightly to compress the silicon slightly, then leave it alone. I don't have any pictures of my silicon beads -- it was a warm day and I was trying hard to get each hatch in place immediately after applying silicon.

I don't think I was applying enough silicon on the first few hatches, based on the lack of squeeze-out; I'm not too worried since I know it's under there, but it'll be something to keep an eye on. An idea just occurred to me that I'll have to try: I can do leak-testing with the garden hose.

After leaving the hatches alone for 3-4 hours to cure (probably not a full cure, but that's as long as I was willing to wait), I got started attaching the nuts and washers. I used stainless steel machine screws and nuts purchased at Fisheries Supply in Seattle; it would have been more cost-effective to order in bulk, but I was in a hurry. Unfortunately F.S. was out-of-stock on S.S. lock washers, so I resorted to using flat washers plus some Loctite on each screw.

The large access hatches are pretty easy to do, but the 6" hatches can be tough to maneuver in. I was using nut-drivers which helped a lot but still had to wrap some masking tape around the nut-driver... hold each washer in place, otherwise I was dropping them all the time (buy extra washers and nuts, so you don't find yourself cursing when you drop one into the float). Quite simply, this is a tedious job that can't really be rushed.

The final result:

Both floats are now buttoned up and winterized for a nice PNW winter.


Tom McCaw said...

God I love the Internet. If I had to give up the TV or the Internet it would be the TV. Thanks for the pic Jay of the side of the float. Your floats look awesome. Just a word of caution… when you start to work with plexi glass do not use Loctite, plexi hates chemicals... the Loctite will make every hole craze in a day. Man oh man I got to get the shop done.


Menno said...

Thank you for making and updating your excellent blog. I visit it really often.

I'm building a F22 as well (in the Netherlands) and started a blog as I'll start building the main hull soon - it might be interesting for you and the other f22 builders to watch the progress.


GK said...

Jay, well done and congratulations on the completion of the floats. It is a real milestone to have achieved. Your fearless in-depth descriptions have been extremely helpful for me this summer. One comment though, what about the non-slip surface on the float decks? Will you add this later?

Grant F22 #12 Raven

Jay said...

Tom - you're quite welcome, and thanks for the Loctite warning. I used it only out of desperation, because I didn't want to slip my schedule. Future attachments will be with lock washers only.

Menno - I'm glad you find the blog helpful. It's awesome that you've started a blog as well. By the time we're all done, there will be almost zero mysteries for new F22 builders to worry about. I started looking at your blog; loved the pictures of the floats being lowered from your attic. :-)

Grant - I am definitely going to add a non-slip surface, and am planning on using the stuff sold here: However, I decided to delay this step until I have the beams attached (so I can mask the non-slip around them).