30' cruising catamaran repair log

Somebody asked how much this weighed and how it compared to a store bought aluminum boom. I don't know what the other booms weigh of equal size (13') and strength - possible about the same or maybe even a bit lighter, but this will be ok. At this point, I weighed it with the sheave boxes (minus sheaves) and it was at 46 lbs. With the rest of the glass and carbon and whatnot, it'll be over 50 lbs. I'll weigh it again when all finished, perhaps.

Here's a few pictures of getting the last of the full length carbon fiber and fiberglass on the boom, using a vacuum bag. Was a bit worried about vacuum bagging the whole boom in a bag as I wondered if I could crush it. I tested it first with a leaky bag - not full vacuum, and slowly closed up the leaks. It seems pretty stout, so went with it. I just use a shop vac so not sure I have the strongest vacuum anyway.

But it still laid down the fiber pretty good and sucked some excess epoxy out of the mix. I did have a few wrinkles in the carbon - not sure what I do wrong there as it was nice and smooth when I put down the peel ply. Must have been as the bag sucked up, it pulled a bit on the carbon as it sough equilibrium.

 

And here I am getting ready to set the sheave boxes. I put some Saranwrap (plastic kitchen wrap) around the base, then added some thickened epoxy under the boxes and pushed them into place, hoping the epoxy will squeeze out and create a nice little socket for the bases. The boxes will be removeable (I hope) so I want a good base that the boxes will be screwed through - the epoxy should help resist some shear force on the screws. The boxes will bear against the boom where they exit, to help resist force there, and the sheaves will be pinned through the sides of the boom to further help hold them in place. I'll reinforce the sides of the boom a bit where the tops of boxes bear against, and where the pin exits the sides.

 

Fairing and rails for the boom. Using pvc conduit for rails, to be wrapped in fiberglass and insert dowels into them for stiffness. Had to make my own dowels as store-bought ones were too small in diameter.

 

Got your post on the trailer. The trailer started as a equipment and log hauling unit. When I purchased the boat the yard had a pile of steel square tube from 4 x 6 to 8 x 8. I will need to look through for some pictures but basically I extended the hitch, set a cross beam of square tube at the front and back then used a smaller tube that slid inside the trailer mounted tubes and can extend them to catch the hulls. Only sits on 4 spots on the trailer. The pads are about 3 ft. long. Front with rollers back is just wood planks. I will look for some picks. Before I bought my boat I had visited Kurt as my brother lives in the Seattle area.

 

thanks C. Dan!

 

So looked through my picks and have nothing on the trailer. Will be putting the boat in the water in a month or so and will take some picks then. If I remember. Don't do that so well anymore. Looked back through your earlier pages and see you were working steering. I made quadrants for the rudder posts and set sheaves purchased from McMaster Carr I think and those go to the wheel with a piece of chain to the wire. Stainless 1/8" wire and it has been flawless for about 10 years now. See picks. Very smooth and all the power needed but can get a bit stiff in heavy seas. Attached a pick of why I bought my boat pretty cheap. Hand crank winch on an I beam lift for small boats. Sign on the lift says 9000 lbs. At the time the boat weighed about 16,000. Supports parted and it all came down on the boat with the guys daughter standing on one of the front nets. You just cannot fix stupid. After seeing the pick of the wreck and what little damage was done I did not have many worries about strength. Boat dropped about 3 ft. and landed on a steel sea wall and a steel dock. Just a big scrape on the bottom at one of the dagger-board openings needed some work. The gunnel on one side had to be repaired as well. Bigger issue was rotted bottom bridge-deck sheeting. Replaced about 40 sq. ft. Anyway keep the faith getting there is half the fun.

 

Building my quadrant as we speak, so to speak. Thanks for sharing those pics.. nice to see how others do things, which is hard to do up here in my sailboat desert.

 

Boom is ready for paint and mounting of sheave boxes. Here it is with some coats of epoxy to seal up the fairing:
Second pic is sheave boxes ready for paint and installation.

 

Took some time to cut the notches for the netting or trampoline between the hulls:

 

For steering, I had to make some tiller shaft bushings. I wrapped several layers of biaxial around the waxed aluminum shaft. I cooled the shaft off in snow and hit it off with a hammer and board. Then glued up one bushing into the quadrant (after building up the business edge of the quadrant with glass to cut grooves for the dyneema line).

 

Next project was building the gooseneck bracket. Not knowing much about sailboats, I found it very difficult to know what off-the-shelf type bracket to buy without being able to actually see them, hold them in my hand. A lot of the catalogs I found online didn't have dimensions. Kurt provided a size in the drawings, so I decided to just go ahead and build that. Now I need to find a local competent aluminum welder.

 

Next was figuring out steering geometry and building some more parts. I had to mock it up in wood for the rudder tiller and rod that will connect to a car on the rear beam in the center. Started glassing the tillers after getting the rough shaped, to a bit over 1/4" thick. Still will need to round the edges off a bit. And today I cut the grooves for the dyneema in the quadrant.

 

A few days ago Kurt suggested I could use wind surfer board masts for the rods that connect the rudders. I searched online a bit and it looks like those are now out of favor for kite surfing. Which could be good.. a kite surfer may have a mast he no longer uses and would let go cheap. I guess some of these guys have a few, or used to. Much to my surprise though, I was able to find one in Nome. The guy gave it to me. I'll still need to find one more and have to pay the ship charges to air freight it up, but cool, nevertheless. This one is about 15', so as I need 2 at about 8' plus a few inches, it is too bad I can't cut it in two. But it does taper so wouldn't match anyway. i think some of the masts actually are 2 piece, which would help with shipping costs if I can find another. Sail came with it, which maybe I could re-purpose for a dingy or something?