Home Building BigCat 65, by Tim Dunn

I am the designer of BigCat 65, which I designed for my own use. At the bottom of this page, you will find a link to the design information for this somewhat unusual 65 foot sailing catamaran.

As I am very arthritic, I am hiring labor to do most of the manual labor on the boat. The going rate for this is $11 an hour, which plus payroll taxes equals about $12 an hour. I guestimate that this will add about $50,000 to the cost of building the boat.

Step one of the building required that we prepare a place to build. I live on 5 acres about 35 miles north of Seattle, and have a metal working shop on my property already, so all we needed was a building shed and a pad outside for finished parts of the boat. I settled on a 34' w x 17' h x 72' long tent structure from Farmtek.com. This is a quonset hut like structure that made of metal pipe and a very heavy vinyl tarp. We had blacktop laid for the pad, and for a strip that we would move the first hull onto while we built the second. The blacktop cost roughly $6,000, and the shed cost about $8,000 with shipping. I hired a crew to erect the building, which cost another $2,000 or so. I also purchased aluminum coated bubble-wrap type insulation to insulate the shed. This cost an additonal $1,200 or so. I have a forklift, so that was no additional expense. I made a sort of pulpit box to hold a man and raise him with the forklift, and we used that when working on the shed. We also used the top of a small cube van that I have to stand on top of to help erect the building. The pipes forming the framework were so floppy that erecting the building was a challenge.

Step two was making the laminating table. Since this boat is similar to a large stitch and glue plywood boat, but with us making the sheet material to fit out of fiberglass and balsa core, we need a laminating table to make our sheet material on. These laminated parts are large pieces which we will lift into the cradle to form the parts of the boat, using vacuum resin infusion. The topsides (the part of a hull that is above the water,) are going to be made in one piece for each side, so we will be making flat sheets almost 65' long and about 7' wide.

The laminating table must be flat, plumb, level, and square, and it is 70' long and 8' wide. It needs to be very smooth, and the surface has to hold a vacuum and resist disolving in styrene. I selected HDO as the material for the top of the table. HDO is a plywood that has been coated with a layer of phenolic plastic reinforced with a bit of fiberglass. It is normally used for making forms for setting concrete building foundations, and I sourced it at a specialty shop for concrete workers. To form the base of the table, I used saw horse brackets from Ace Hardware, 2 x 6s for the tops, and 2 x 4s for the feet. I got levelers from a cabinet maker's supply website, (like those under a washing machine or clothes drier,) to make getting the whole table level easy. Because we were using, essentially, a parking lot for a foundation, it had 4" of slope and wasn't very smooth. We also used blocks of wood under the levelers to help level the table. The joints between pieces of HDO are 6" wide 3/8" plywood screwed from the bottom and glued with 'Liquid Nails," a viscous construction adhesive used in homebuilding.

We are just now starting step three, which is making the 'cradle,' or mold. This is a structure that is a negative of the boat, but in skeleton form rather than covered with a surface like the typical fiberglass boat mold. You can see the parts of the cradle corresponding to sections 6 and 7 in the photo.

To do this lifting and moving of laminated fiberglass / balsa sheets, we will use chain hoists mounted to a movable gantry crane. (Cost about $4,400 with two chain hoists and two trolleys.) This is a structure that weighs 1,600 pounds, almost a ton with the chain hoists and trolleys. It consists of a 20' steel I-beam and adjustable supports with casters to hold it high over head. It came in pieces, and it took two man days of hard work to erect even with the help of a forklift.

I have decided to build a mold for the hull bottoms, and build them so that the solid fiberglass bottoms will be made in one infusion from the bottom of the hulls to a point about 2 feet up from the bottom of the hulls. After we finish the cradle skeleton, we will infuse panels to form this mold on the table, using polyester and glass mat. These molds will be a permanent part of the cradle bottom. If that is not clear, it will become clearer when we do it and I post photos of them.

We vacuum tested the laminating table and found that there were flaws in the wood under the phenolic plastic, and that the phenolic plastic above the flaws wasn't strong enough to resist the vacuum and collapsed. So, we laminated glass mat the the table, after sanding the plastic. The above photo shows us resin infusing the table. It isn't a very good laminate from a strength standpoint, inasmuch as it has air bubbles in it due to the flaws in the table that let air into the laminate while we were vacuum infusing it, so we sanded it and coated it with two layers of resin by hand. After that we put on some Duratek EZ sand, a sandable gel coat.

We found that the resin was setting a little too soon when we were infusing the table top, and so it was constricting the resin feed tubes about 1/2 way into the infusion. We were feeding the resin in at one end of the table only. In the future, we will have valved auxiliary feeds in the middle of the table, so that we can avoid trying to feed resin through parts of the lines that are hardening.

We have finished grinding the table, and are putting a coat of sealer and 7 coats of wax on it. We will start laminating the hull bottom mold after we finish insulating the ends of the tube tent-It's now late October (2008) and it's getting a little nippy.

My new helper is Miles Daniely, who has been building fiberglass boats for 7 years. There are a lot of fiberglass boat workers out of work right now around here, as local boat builders Glacier went bankrupt and Meridian Yachts(aka Bayliner) has permanently closed its local factory.

Disaster has struck! An unprecedented snow fall has collapsed my tube tent and damaged my mold. Life is like a board game, and I have just drawn "proceed directly to jail." We are currently erecting a pole barn over the remains of the tube tent, which we will demolish after the pole barn is erected. We are doing it in this order so as to be able to tie up the remains of the tube tent to the pole barn as we demolish it, so it doesn't fall on our head. Of course, now that the snow has melted, the ground is wet and muddy, so we keep getting heavy equipment stuck in the mud.

The pole shed rises over the wreckage of the tube tent.

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For information about the design of the BigCat 65 catamaran by Tim Dunn, go to: BigCat 65 Catamaran Design page

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