Building power cat hulls

I took on the job of building a set of hulls for Kurts 28’ power cat design which we stretched to 31’ by adding about 2.5 inches to every station. We upped the stringer size by 30% and glassed with 8oz rather than 6oz but otherwise stuck with the plan and laminate schedule. We used multiple layers of 8 and 10oz to make up biax tapes, i find it makes for easier fairing and allows for tapering the buildup. We did a half-way-to-yacht quality fairing job, primed with 545 and installed cleats, hatches, fuel tanks, and fuel fills. There will be lightweight 25 hp engines mounted on rear transoms. We finished both hulls and shipped to the owner in maine, who is going to build the cross arms and center cockpit over the winter. I really can’t recommend committing to building a boat over the summer in sarasota, florida in a non-airconditioned space, but, in the spirit of running a marathon, and other ridiculously painful ways to enjoy yourself, we did it.  Total build time, including purchasing, hardware, and mounting on a trailer for shipment, was in the neighborhood of a thousand hours. LOTS of pictures after the break-

Stringers

Stringer scarfs

Glued up

Gluing a pair of deck flange molds

Scarfing 3mm

assembled mold

Bagged hull halves

Trimmed

Sheer clamps applied

Hulls spread and initial glue

Bow clamped around 3/4 composite

Bulkhead patterns

Fuel tank fit

Decks

Lots of clamps 😉 – aft end can be tricky, especially if you trim it early – but wire ties work wonders

Bagging aft cored deck

Dry glass

Sanding

Tramp attachment – just after filling into tape and before glassing.  rod was removed by hooking up to a  12 volt battery for 30 seconds

Painted!

Standing in front of #1

in the midst of hardware installation

Off to Maine…

Here is the link to kurts plans:

http://www.multihulldesigns.com/designs_stock/28cat.html

4 thoughts on “Building power cat hulls”

  1. Nice build job there.

    I remember when I did my 3rd ama, I I did a 20 footer to the point of “fuel tank fit”, in 20 hours. using Stressform (these were much narrower hulls that here). It was my third hull and I had the deck jig, and the pattern, I can’t recall if I had something major like the hull panels scarfed. I know there was something hanging around the shop while we built the main hull. On that basis the whole tri should of taken 3 weeks, :). In fact it took 7 months. And a lot of time messing with details outside the shop, doing the parts assembly. It is hard to figure where all the time goes…

    Hot sounds good, we did all the building over one winter.

  2. Flat decks? No camber?
    I’ve always wondered: is it better to fill, fair and glass
    Or in this case, glass. Fill and fair?

  3. hi andrew, the decks are cambered about 20mm and are built from (bottom up) 5mm ply, 14mm balsa, and 3mm ply. I like doing all major filling/fairing under the glass, leaving only minor filling over the glass.

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