Building 23' catamaran. Build updates

[chris69]

Hi there Steve just put your measured amount of epoxy your going to use for a mix in the freezer for 5 mins but put the container in a bag and this willl help,if im doing bigger mixes of epoxy im putting a 4lt container in the freezer for a hour and then i keep it in a esky and im also useing aluminium roasting trays to transfer heat ive been mixing 1.2lt brews ok in 29c ok you just have to work fast use a roller to get it out quicker,when mixing cool epoxy just mix it for a bit longer,it looks lokie a good kit to build the endgrain balsa will be good to work with,and also the outgassing you just have to pre wet and let it soak in and you can let it go tacky and then chemicaly bond the sheating and fillets of bog,and when mixing the bog filler spread it out around you container and get it out quick so it dosent go thermal on you.

[stevemid]

Hi there Steve just put your measured amount of epoxy your going to use for a mix in the freezer for 5 mins but put the container in a bag and this willl help,if im doing bigger mixes of epoxy im putting a 4lt container in the freezer for a hour and then i keep it in a esky and im also useing aluminium roasting trays to transfer heat ive been mixing 1.2lt brews ok in 29c ok you just have to work fast use a roller to get it out quicker,when mixing cool epoxy just mix it for a bit longer,it looks lokie a good kit to build the endgrain balsa will be good to work with,and also the outgassing you just have to pre wet and let it soak in and you can let it go tacky and then chemicaly bond the sheating and fillets of bog,and when mixing the bog filler spread it out around you container and get it out quick so it dosent go thermal on you.

Hi Chris,
I do have a fridge at the shed so I'll give that a try. For now, in the early stages the jobs lend themselves to doing things in small batches. Even when I start assembling the hulls (upside down on the build jig) I can glue and cove one chine at a time. The fun will start when I have to apply dbl bias over an entire hull. Leading up to that I'll experiment with the fridge.

On the outgassing issue, lots of designers use the composite sheets from ATL. My designer, Craig Schionning of Spirited Designs said that ATL do recommend sealing the exterior of their panels. He has never run into the outgassing issue but then he recommends the following 5 stage sealing process:
2 squeegee coats of West System resin on the panels before assembly, and then, after assembly:
1 coat of bog and fairing
1 squeegee of West
HB primer, then
Paint system

Cheers,
Steve

[stevemid]

It's been a while since I posted an update so I'll get busy. After gluing up all the panels, I cut out the components that make up the hulls. Everything else I stored in as large a pieces as I could. The first step for the hull components was to fill the screw holes from the clamping process then squeegee on two coats of epoxy. The 75mm margin which was not sealed will be sealed when this part is joined to another part of the hull. It would be easy enough to squeegee the whole part but then you end up with a shiny hard surface that doesn’t bond easily to its neighbor and since it gets coated in the joining process, it’s easier to leave it raw.

IMG_0175.jpgIMG_0168.jpgIMG_0177.jpg

[stevemid]

After prepping the components, my next step was to assemble the build frames. I had a bit of too'ing and fro'ing with this. The shed is 7.3M deep and 13M wide. The boat is 7M but the build frames are 7.5 M. I tried this diagonally in the shed and ended up deciding that straight in was best. However, not without compromises.

The picture of the build frame shows the "deadrise issue" with a cat is a non issue. Effectively the dead rise from hull to hull is "0" leaving a very stable platform at rest. At the bows the hulls are very fine leaving a very fine entry and (hopefully) no slamming.

[stevemid]

Today I finished getting the build frames square and level. I used a water level. In the first picture you see the main deal: an upside down 1.5L coke bottle with a bung in the neck through which passes one end of a 20M plastic tube. Since I believe in better living through chemistry, I added some dishwasher rinse agent (lubricates the insides of the tube) and food colouring to the water (to help my tired eyes.)

The bottoms of all my frames are designed as a common level point. Since it is difficult for persons of a certain age to get down to the floor, I measured up about 1.2M (4 ft.) all the way around on each frame. I used the device in the second picture to make sure all my marks were exactly the same distance off the bottom of each frame.

Next I went around to each station with the end of the tube to find my “highest point.” Once that was found, I set the reservoir on that point so that its level matched the mark on that station. Then it was just a matter of taking the tube around to each station and shimming the station up to match the reference point (pic 3.)

Actually this sounds easier than it was because changing one point alters everything it is attached to. (for example changing a station to make it square with the spine also changes its level, and change one end of a station alters the position of the other side of that station. It took me a couple days to get it right. Now I’ll let it set for a day or so and check again. Once it is stable and completely level and square, I’ll epoxy each part of the frame to the cement floor.

[rando]

Clever solution,
Congratulations.
Very enjoyable read,and i look forward to following your build, thanks very much for sharing the adventure.

[stevemid]

Progress Report

All the hull panels have been dry fitted to the frames. A little argy-bargy at the bow to work out where the panels all come together...A few gaps to fill....A bit of grinding here and there. At the end of it we're ready to start bogging and glassing the chines. Very satisfying to see the boat start to take shape.

[HH565L]

I've been following from day 1 and intend to stay tuned until completion. Hope you don't mind

I take my hat off to you for taking on a project of this nature and look forward to watching this evolve from a stack of sheet to finished boat.

Thanks for sharing.

[stevemid]

Once we had all the hull panels “dry fitted” the side panels came off again so we could fillet and fiberglass each of the chines (where flat panels come together.) Recall that the boat is being build upside down, on a set of frames. At some point the hull needs to be taken off the frames and rolled right side up. However, to do that, there needs to be enough strength in the hull structure to take a good roll. That means it has to be glued on the inside and the outside. For the inside, the chines have to be glued in the sections between each frame and once the boat is turned over and the frames removed, the job completed. The outside is next; that is the easy part: no scrunching down working above your head with epoxy falling in your hair.

The last picture shows the cuts we had to put into the front of the hull side panel to get the panel to curve in to form the pointy end of the bow. Once we had it dry fitted, it came off so we could glass the chines on the inside of the boat. Before it went back on we filled the cuts with thickened epoxy (this will help the panel keep its shape) before reattaching the side panel and forcing it back into position.

[chris69]

Looking good there Steve the old water level is a good thing,gee theres a bit of work in that jig and that end grain balsa looks alright,atleast it will be light to turn over,cheers Chris.

[stevemid]

Hi Chris, Yes, I haven't decided yet how to turn the thing. I have height restrictions that prevent me from lifting the hull off the frames. I'm thinking I could jack or lift up the hull off the frames, then cut the frames out from underneath with a chain saw or other. Once the frames are out I can assess the weight and gather enough men to walk it out the door to turn it on the grass and then walk it back in. I'm going to install the transom when beforehand so that plus a cross frame in the middle should be enough to stabilise the hull for the turning. Option two is to put sleds underneath the frames, drag it out of the shed with a 4WD, then I could turn it with the frames in it, then remove the frames and carry it back in.

[stevemid]

In the couple weeks since my last post we finishing taping the external chines on the boat. Here is the result.

IMG_0267.jpgIMG_0269.jpgIMG_0270.jpgIMG_0274.jpgIMG_0278.jpg

[chris69]

Thas looking real good steve you have been flying on this boat seeing the endgrain balsa gives me a tingle down my spin way stronger than foam core in compression strenght thats going to be one tuff boat,cheers Chris.

[stevemid]

Thanks Chris, we're putting on a layer of 400 DB glass over the whole of the underwater section, then fairing and antifoul. Then the turning party.....Can't wait.

[cormorant]

Did you see the turning rings in the afloat mag. Thought of you when I read the add if you have a space outside the shed. I haven't seen em but would be interested to see a photo if you had a look.

Love teh progress on the build.