Saturday, 31 March 2012

Back to the main problem - dampness in the foam

Getting back to the catamaran after a break building the dinghy, I spent a day mapping dampness in every part of the boat with the moisture meter. I'm not sure why I haven't done this as thoroughly before. Most of the problem areas are in the coachroof, but there's a bit of water in the starboard deck, and there is dampness in the hulls close to the daggerboard cases. It seemed like a big problem and I spent a day regretting not building my own boat from scratch so that I am not chasing around problems caused by other people's poor workmanship. And wondering what the hell to do about it all. How to get the water out? How to assess the damage the water may have caused? Maybe I can just get the water out in some areas, and the laminate might be OK. Other places I'll have to replace fibreglass, or both a layer of glass and the foam beneath.

When you've got a big problem that you don't know how best to deal with it, find someone else who is already dealing with the same problem. Or even better, someone with a bigger problem that can put yours into perspective.

There's a boat yard just 400 metres from my house. In a shed in there is a 39' foam sandwich catamaran that has the gel coat stripped away to deal with an osmosis problem. Water is dripping out in a couple of places. With the gel coat removed, the outer layer of glass is clearly visible, and the foam below that. I went to visit with my moisture meter. I was relieved to see that where the moisture levels were high, there were very few places that had any sign of delamination.

A 39' Catana with the gel coat stripped off.

Clearly, my boat needs drying out, and the sources of the water ingress dealing with, but the repairs to the laminate may be necessary only in the worst affected areas.

I've decided to bring my cat to the same yard, and put it in the shed there for the summer. I doubt I'll have to strip away the whole of the gel coat, but repairing the laminate will require warm and dry conditions.

So there goes my summer sailing. But if I sail back down the river at the end of the summer with a solid dry boat, newly painted and ready for the high seas at last, I'll have plenty of confidence in what I'm sailing, and I might get it all done in time to sail south of the winter.

Monday, 26 March 2012

Launch day!

A friend has offered to paint the dinghy in his car body shop, using two-pack polyurethane paint. That will be great - so I wanted to test the boat in the water in case there were adjustments required first.

The front half floats.

Goes together OK.

First row - floats right on the planned lines! Hooray!

Goes OK with the outboard, but needs a tiller extension to get the trim right.

Or add some more people. Daughter Sif at the front, Tom, and the smug fella at the back is someone that looks like me.

A few minor adjustments needed. I'd hoped the central seat would be enough to hold the boat together, without any use of bolts or complicated connecting systems. It's nearly enough. If I make some wooden clamps to hold the top edges of the connecting bulkheads, it'll hold together just fine. I did a fast turn and drove through the waves I'd just made. A very small amount of water found its way into the boat through the connecting bulkheads. I think a piece of draught excluder will be enough to keep out those splashes. And I didn't make the outboard pad thick enough. But those are quick and easy fixes, so I'll save them for a rainy day, and get back to the catamaran tomorrow. 

Saturday, 17 March 2012

How to slice up a boat

The rub rail added, which gives the dinghy a lot of stiffness,

but now, for a man that doesn't like to have holes through a hull, this took some doing...

It was light enough to be moved around easily before I cut it in half. Now the parts are very easy to handle. I intend to assemble the dinghy on the water, so the two parts can be lowered into the water separately. I am also determined to forgo holes in the bulkheads, and not to have any nuts and bolts or complicated catches or seals. Watch this space.

 It stores neatly now:

Tuesday, 6 March 2012

A pleasant distraction

Clearly, fixing up the coachroof is a major job, but not something I am even going to attempt until the weather improves a great deal. For now, best not to think about it too hard.

Some exercise has helped my back problem, but lying around twisting this way and that, I realised that doing something like lifting an outboard onto the back of a dinghy could be just the sort of thing to put me out of action for a good long while. I'd be much better off with a dinghy that rows well. I'd be getting the right kind of exercise to strengthen my back, and there'd be one less noisy outboard to feed, maintain, and keep secure.

A dinghy that rows well is long, too long to fit on my boat. So I figured a nesting dinghy would be best, one that comes apart, with one part stored inside the other.

The platform at the back of the boat is a metre wide. It could store a dinghy, but some of it would be hanging over the back. I think that would be fine for short journeys, day hops, trips in nice weather, but where there was a chance of heavy weather, I'd prefer the dinghy stored in the cockpit where the weight is more central. I'd have to leave room to walk around it fore and aft, but that leaves me 6 feet or so. With a 5' front section, I could have a 10-11' dinghy.

For the dinghy to fit just where I want to store it, and for it to be as big as possible within that space, I'd have to design it myself. A stitch and glue job would be nice and light, and I could design it to be as commodious as possible, so as to allow for rowing with 2-3 other people in it.

The free hull design program here was a great help. I imported the curves it produced into another CAD program, and saw that the curves weren't that even. I smoothed them out some more, and generated the numbers that would allow me to layout the panels. That was fun. My first boat design.

First I made templates using wallpaper, then laid them out on some 6mm ply (poplar core, nice and light):

Cut out two floor sections and stitched down the centre of the floor with wire:

Open the two parts out:

Add a side and the stern:

As I was working alone, I needed to use parcel tape to hold the parts roughly in position, so that I could stitch them together with wire. You can see the butt block on the side - a piece of scrap ply I've used to join the panels together where. I used a little bead of polyurethane glue for this so that I can remove the butt blocks once I have finished epoxying the boat and added the rub rail. The join is right where the boat will be separated into two parts.

Here's the rest of the parts stitched together:

Perspective seems to make the bow oddly too big, but in real life, it's exactly as I'd planned on the computer. Very satisfying. Assembly took just a morning!

Here's a bulkhead I added where I will saw the boat in two later. I've made two bulkheads, and joined them together with some corrugated cardboard. This will allow me to saw through nice and easy with a hand saw:

This pleasant work was quite a contrast to messing with wet foam and delamination down the cat on the river. It's occurred to me that if I find more delamination, one possibility it to use a grinder to chop off the whole of the coachroof, and transport it to the workshop where I can sort it all out without being interrupted by the weather.

Dinghy building seems like an escape from the more serious issues but planning the work according to the weather feels like a more seaman-like approach than battling on!

If anyone is interested in the plans for this boat, here are the plans in an A4 pdf file. 

The dinghy is 3177mm long and 1220mm wide at it's widest. You can make it with 3 8 x 4 sheets of ply.

You may want to wait till I publish a photo of the boat on the water first though!

A disappointing discovery

Delamination! Aghhh!

There's something wrong with my camera too, which is why the top right of the image has that pattern on it.

I was playing around with my moisture meter, and looking around the coachroof closely trying to find the source of a small leak. I'd thought the leak was from the bolts attaching the hand rail to the roof, but I've fixed that. Then I noticed some small holes in the gel coat...

The moisture meter shows red in the area I've marked with tape and a pencil line. I drilled a few exploratory holes, and didn't like what I found, so chopped out a square, and here's what the sample looks like:

The foam was barely attached to the outer skin, and blackening between the skin and the foam shows the extent of the damage. I guess the damage is limited by the size of the foam panel - neighbouring panels are unaffected.

Clearly this section of the roof will need to have the foam replaced. And while I am doing that, I may as well dig exploratory holes all over the roof, wherever the meter indicates any dampness. But this job is for later.

A fog came down, and my back which has been giving me a lot of trouble lately, started playing up. Driving home in the fog, in pain, contemplating this new problem wasn't a lot of fun.