dinsdag 26 mei 2009

Fitting folding system + floats

This will be a bit long and maybe boring post, but I thought some of the other builders would be interested in as much details as possible about my experiences fitting the beams.

Saturday and sunday me and my brother Hans worked hard to get the folding system and the floats installed. Saturday we worked on the folding parts on the mainhull which was on its trailer in the marina. Saturday evening we pulled the trailer with the mainhull to my workshop. The square in front of my workshop is used for parking cars from monday till saturday, but on sunday it's usually not occupied. So I had one sunday to install everything and move the boat again.

On sunday we started working at 8 in the morning, and worked almost non-stop till 9 in the evening. By then the boat was assembled enough to be able to bring it back to the marina (about 1 hour drive). My idea to pick up the mast on the way back was too optimistic. I'll have to drive back another time to pick it up.

First thing we did was fitting the bushes in the beam mounts. This can be easily done by sticking the bush with some double sided tape on a sawblade and use that to insert the bush in the mount.
Then we leveled the trailer (used a tube with water to level; when you do this make sure there are no air bubbles in the tube). With the trailer leveled we attached the upper folding struts to the hull and then to the beams.
This took more time than expected, because on one beam mount the holes for the bushings were not in line (see last part of the linked entry). The pivot pin would not properly go through both bushes because of this misalignment, and we had to use a lot of force. Destroyed one bushing in the process, but luckily I had a some spare bushings.
The fit of the beams in the aft beam recesses was not perfect. I had to grind one beam end back a bit to make it fit in the recess (but not as much as the line drawn on the photo below).
Because I knew I didn't have much time to install the beams I made two dummy decks of the floats (below - box sections of fir battens with cheapo 3 mm multiplex) so I didn't have to worry about the distance between the beam ends nor the twist of the beams.
I don't know if it would have been difficult without the dummy decks, but with the dummy decks aligning the beams was a piece of cake. First we put the end of the dummy decks on two ladders and put blocks and shims underneath until the beams were level. Then we clamped some battens along the edge of the dummy decks and used a rectangualar piece of mdf to check if the angle between the beams and the dummy deck was 90 degrees (see photo below).
With the level and the piece of mdf it was easy to quickly recheck the alignment now and then during the installation. I was a bit worried the fore-aft alignment of the beams would give problems as I had noticed that at least one beam mount was a bit out of angle fore/aft (it was pointing slightly to the front), and apart from that for some reason I managed to get the location pins of both floats about 8 mm too far apart. But much to my surprise the vertical alignment of the beams seemed near perfect. Maybe by miracle I also installed the beam mounts 8 mm too far apart, but more probably it's just hard to notice the few mm misalignment.

On all four beams it seems the beams are sticking out a bit too far at the beam mount, and I will have to grind the end of the beams (maybe even considerably on some beams) to make space to fit the beam end plate. Thought this part of the alignment would give the least problems and the fit would be the most accurate, but clearly it is not so. Don't know why.

The brackets all fit on the bolting area perfectly. Big relief again.

After aligning and bolting the beams+folding structure we had to hoist the floats down. This time not with a crane, but with some lines and chain hoists.
Yes I know, this is not a very smart way to hoist a float. Still the floats came down with not too many scratches.Bolting on the floats was not difficult either. We folded out the beams, put two workmates underneath the beam ends, lifted the float on the workmates and while one person held the float steady at the bow, the other put some blocks under the keel till the beam bolts stuck in the float deck at one beam. Quickly put a nut a few turns on one beam bolt and it's temporarily fixed. Then fix the float at the other beam the same way. It's not necessary the float stays level: it's possible to put the beam bolts on one side in the float deck with the float hanging, say, 20 to 30 cm below the other beam end.

After fastening four of the six bolts per beam the boat was solid enough to fold in and drive it back to the marina. I still have to glue all the brackets and beams and to fix the beam end plates.
The folding works very well, it's something you've got to see/feel for yourself to believe.
Below the boat is ready for the ride back.

Detail below: I replaced the stainless steel trailer eye by a loop of 6 mm dyneema with a knot on the inside. Easy and it seems to work well.

I never realized how wide the folded boat was at the bow end, but now I do.

Last photo: getting the trailer out was only just possible.

To conclude some lessons learned/things I noticed:

  • It's not necessary to level the boat lenghtwise to install the beams. It's sufficient to make sure the left and right beam mounts are level. When the boat is on a trailer (make sure it's tied down firmly on the trailer) this is easy: put fixed blocks under the front end of the trailer and one of the two aft corners, and jack the other aft end of the trailer until the aft beam mounts are level. Front beam mount should now also be level.
  • Bolting the aft beam compression formers with the four bolts is terrible. There is by no way enough space inside/underneath to get all nuts on with washers. I even had to redrill two bolt-holes at a *very* slight angle to be able to get a nut on. Maybe it can work out right on a computer screen, but I doubt ever in the real world.
  • Important for european builders: I thought the bolt blocks hanging inside the beam mounts would be tapped M12, but (should have known this probably) they were tapped with a non-metric thread. I had no possibility to get the right bolts on sunday, and had to turn in my M12 bolts in anyway. I probably damaged the thread too much and I will have to replace those blocks.
  • When making /installing the aft beam recess mold plates, rather err on the 'big side' because this area is tight when done properly and too tight when you make the recesses by mistake a little bit smaller than per plans.
  • It's easiest to line up the metal hardware on the aft beam mounts by first only putting in the outer bolts left and right, and then use a wire or a long straight piece of wood/metal to put the hardware on both ends exactly in line with eachother. This way you can correct any possible misalignment of the beam mounts (in case they are angled a bit forward or aft).
  • The holes on my beam brackets were all a bit less than 10 mm diameter and I had to redrill all the holes. Better check & fix this before putting the folding struts on the beams.
  • Fix your main hatch while driving. Maybe it's enough to firmly fix the front legs of the hatch. I thought the driving wind would always be pushing the hatch down, but while driving the wind got underneath and the front popped up. The hatch then acted as a big 'wind trap'. Good thing is now my whole boat has had an excellent ventialation.

2 opmerkingen:

bucko00014 zei

Hi Menno , great report , you should be sailing in a couple of weeks ........Cheers , Jim Buckland .

Roger zei

Hi Menno,
thanks...
We can all take out advantage from your precise description. Nice work. Let us soon know how the boat will sail.

Roger