hollow wooden surfboard workshop

 
   more infos on www.arbosurfboards.blogspot.com

stringers

the stringers we use are all sitka spruce from robbins timber in bristol.  they come in a lenght of ca. 5500mm ready machined to a thickness of 35x25mm and in good quality with very few defects and nice straight grain.   we only have to thickness them down to 35x22mm and scarph them to the required length. before scarphing the lengths together we coat them in epoxy and round off the corners that are going to be facing inwards.  doing this before scarphing makes handling much easier.

we find the quickest way to coat a lot of stringers at once is to clamp them flat together, apply resin with a roller or brush and take them apart once the epoxy is gelled so they do not get bonded together.  don’t wait too long… we coat on face side (35mm) first, coat the opposite 35mm side, then round of the corners and do the rounded side at last. the second narrow side is left bare and gets a quick saturation coat before the planking sheets get glued on with spabond.

routering the corners where easy on a simple router table set up but even easier freehanded with this priceless little fella :

 

for the scarph joints we used a 1:12 ratio which were easily cut on the radial arm saw with a little jig.

clamping them together in a jig with spabond from sp systems…

…and out come enormous lengths of spruce …

…with a nearly invisible joint line.

shame that none of that wood will be seen in the finished boat…

our workshop

i wonder why the cops have not been here yet. a well insulated greenhouse, the light is on till late at night, owned by a dutchman… i would think some marihuana growing is happening there. 

setting up bulkheads II

when we first set up the bulkheads we just located them on their correct position, in the right height and perpendicular to the centreline at the base. they were still able to lean for or backwards and to twist between sheer and keel line.

with a temporary keel we stopped the bulkheads from leaning and fixed them plum in position. the laser we used earlier to establish a centreline and to set the bulkheads level was helpful again.

on the picture above you can see the temporary keel in the middle and the sitka spruce keel stringers before they are glued in.

some of the bulkheads, specially the ones with a quite big cut out in the middle and therefore narrow at some places, were not stiff enough to remain straight under the load of the keelstringers. some bulkheads were slightly bowed because the flocoat cured whilst they were leaning against a wall and the epoxy fixed their slight bow. with the help of additional stringers on each side we straightened them up again.

we clamped the stringers in position and used laser, plum bob and tape measure to do fine adjustments until all bulkheads were straight and plum. in order not having to do all that again we marked the bulkhead locations on the stringers. when it came to glueing the stringers in place all we had to do was to get everything to the marked position.

to keep accessibility into the hull easy for a long time, we only glued in the stringers on one side of the hull and left the other side more or less open. you are going to see more of that in the next posts.

this is this weird guy who seems to be on a lot of the photographs i take of the building process. one of the rare pictures where he is wearing more than just the headphones and the glasses…

if you need some nice pottery, he is the man!

setting up bulkheads

the first thing we did when we set up the bulkheads, was to locate their exact position fore and aft and mark it on the longitudinal members of the strongback perpendicular to the centreline. using a long tape measure prevented accumulative errors. with a little arrow and a second line we marked if the bulkhead was to be set forward or aft of the stationline.

we build the catamaran upside down and to keep everything level we had to rise most of the bulkheads as can be seen in the picture above. the two floats have a negative sheer so the highest point of the sheer is located somewhere amidships and not like in traditional hulls at the stem or transom. the station/bulkhead closest to this highest point we sat on the strongback which we assume the baseline. from the drawings we could then establish the height of the support risers for the remaining bulkheads.

a quick and easy way to do this was to create slots from three strips of ply. the “sandwiched” layer of ply is cut to  the required height and the two face layers a bit oversized.  so the bulkhead can slide in this created slot and can be clamped or screwed in position.

 

all bulkheads had waterlines and centrelines cut by the cnc router at swallow boats so with the help of a laser it was easy to align them. at this stage we weren’t to worried about having the bulkheads fixed plum as we were using the stringers at a later stage to locate them in their correct position.

the steps to our workshop

those are just the top steps…

it's been a while...

time flies when you're building a boat.
the last months where busy for me finishing college whilst working behind the bar in a theatre in the evenings and working on the catamaran on the weekends. and sailing has to be done as well as surfing...

but this is where we are at the moment with the project.
the bulkheads for hull nr.1 are all set up, stringers on one side are glued in, keel is on, the planking on one side is finished,...

i will post more picture of how we got there bit by bit the next days...

more epoxy coating

epoxy coating of first bulkheads

all bulkheads were cut for us at swallow boats in cardigan, a bit less than an hour drive from our shed.
they balance nicely between well thought, modern and cost effective boat building and classic looking boats made for sailing.

had them cut by a cnc router saved a lot of time and we now have really precise cut bulkheads. all it needed was cleaning up the slightly rough edges and figuring out how the finger joints in the bigger bulkheads would slide together. ..
I hope we can trust the computers who did a lot of work for us and everything is fair and in the right place when the bulkheads are set up...


on the three bulkheads you can see on the picture above. i tried out an epoxy system commonly used in surfboard building called resin research and is distributed in the uk by seabase in cornwall. according to their website, the resin has:

· lower toxicity
· lower exotherm
· longer pot file
· shorter set times
· lower vapour
· better colour
· better colour stability (UV stability for brightwork)
· better strength
· etc.

we still had some leftovers of the widely used and time proven west system resin. so i made a mix of WS as well to compare it with the RR resin.
i was interested in ease to work, gelling time, pot life, efficiency, etc.

when we have used the resin a bit more, i will post more details on our experiences.
so far i can say that the RR resin is a bit more viscous compared to west system what made it easier to use it with a roller sponge and gave a better finish. it is clearer in colour and doesn't seem to give out a lot of vapours so its smell is much less aggressive than WS epoxy. the RR epoxy had a shorted gelling time than the WS but had a longer pot life and was less exothermic when going of in the mixing cup. it must be said though, that we used the slow hardener on WS and the standard hardener on RR.

gelcoating a shellback dinghy for resin infusion

styrene stinks!
at college today i gelcoated a little shellback dinghy. black bottom and dark green topsides.

we did two coats on the black bottom and the transom first, removed the masking tape and did the topsides. there it didn't matter if we were dripping or painting on the black bottom as it will be covered up by the glass laminate on the inside and shouldn't be seen through the black gelcoat to the outside.
tomorrow we're going to prepare the glass, set up vacuum bag, flow medium etc. pipes needed for a resin infusion. we probably will do some test panels to see how quick the resin flows through our laminate stack before we infuse the whole boat.

setting up the strongback for the cat

ysbrand and me set up the strongback yesterday.


we started with fixing the short 2"x4" crosspieces you can see to the floor following a centreline we defined with a really tightly pulled dyneema rope.

we used PU-glue to fix the crosspieces to the floor first but to make it a rigid structure we will drill additional long screws into the concrete floor. last thing we want is a moving strongback.
the people who poured the concrete floor did a pretty good job so we just needed a few strips of ply to get everything perfectly level.

more pictures of the wooden deck

That's what the seams looked like after the first pouring of the glue.
It has already been scraped except the seam of the covering board. You can see little gaps and voids, that are not ideal. They do not look nice and they make it easier for the water to get in.
To fill those little cracks and holes, we used a cheap heatgun to melt the glue in the seams and then poured or rather blew some more glue into the affected areas.
I just cut open an old metal container and bent it to form a nice nozzle. With the heatgun i then was able to blow the glue more or less precisely wherever i wanted it.
Without remelting the glue already in the seams, the new glue wasn't really sticking to it and cracked off quite quickly.

The heatgun was also quite handy when cleaning up after the pouring. In our opinion it was easier to pour more glue into the seams than needed to make sure it is filled. That created a ridge on top of all the seams which needed to be taken off. Just heating it up with the heatgun and then slicing it off with a spatula or an old plane blade worked quite well. It gives a finish like on the picture above on the covering board seam.

And then it's down on your knees and scrape...
We used an old 2" plane blade and a bent and sharpened old file I borrowed from a friend.
The top surface layer of the teak was a bit worn out and was even easier to scrape off after we poured some hot water over it, which also softened the glue.


Here you can see how it looked after the second pouring using heatgun and the small metal container.



















And slowly it starts to look nice...




















The guy I was working for on this project can be found here:
John Edginton at Garron Boatyard in Lawrenny

other things i do

Till i post more pictures of the catamaran project....


I finally finished of a deck today I worked on with colleagues from my boat building college for the last weeks.
Most of the deck planking was still in good condition and just a few short planks on the aft deck needed replacing.



After cleaning out the rebates between the planks, we opened up the seams with a wedge shaped caulking iron. It probably has a better name than that... Dumb Iron is probably the right name for it.
Then cotton went in the seams. Not a lot because the planks were already pretty tight. We then heated up TBS Deck Seam Glue and payed the seams with that sticky stuff.
It is a messy job and after the first few seams we were actually getting a bit worried about this deck being covered in black spots and blobs...
Luckily it scrapes of quite easy. especially if you got this:

Not a lot to see. yet...

Our building shed... an old greenhouse on a sunny hill in lower solva, pembrokeshire. all that insulation created a lot of dust but keeps the temperature quite stable. stable temperature+epoxy=good; dust+epoxy=no good
the man you can see breaking things is Ysbrand. it is his shed, his idea and he will be sailing that cat.