Monday, March 15, 2010

The bottom goes on!


It was quite a busy w/e for me in the garage.

The bottom was joined during the week. I used a staple at each side to prevent “drifting”. My usual car batteries provided the clamping force.

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I took Friday night off and settled in to watch the opening rounds of the RL season with a Coopers and a glass of red (not simultaneously!)

Kim worked on Saturday so I got myself an early start at 7am and finished off bevelling the chines and the bottoms of the bulkheads. The blue steel bars came in handy once more to make sure the angles were right so that the bottom ply edges would sit flat.

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Bulkheads 2 and 3 were a couple of mms low, so they were corrected with a mix of micro-balloons and epoxy and then faired level with a plane and keyed for a good mechanical bond to the bottom. By levelling the BH bottoms first, you can screw the bottom down firmly, knowing it will stay flat.

100_6961 The whitish “cap” is the fairing mix. When the bottom was fixed the filler disappeared from view.

The bottom was dry fitted starting at the bow with just 5 screws along the centreline, one each in the bow, bulkheads and transom. To line up the hull and pull it square, I aligned the bottom centreline with the centrelines marked on the bulkheads. The boat was perfectly straight all the way to bulkhead #3, and then it went skew to side. It was a decent pull with one hand while peeking through the transom’s tiller hole at BH3 and driving the screw with the other! Thank you to the inventor of square drive screws as this would have had potential for disaster with Phillips heads. The transom was easier to align with the bottom as it could be aligned to the outside centreline marking, although it required a heftier shove to move it into position. A quick sighting along the tops of the bulkheads while sitting under the boat confirmed that the hull was in perfect alignment with zero twist. Wow, that was an amazing and satisfying moment!

So GIS builders, don’t worry if your hull isn’t as straight as you’d like as it can be wiggled into shape at this point :)

100_6975  100_6970 This pic shows the 10mm misalignment between the transom and the bottom. An easy fix as it turned out!

After that I predrilled all the holes at 200mm centres which needed to be at an angle to ensure they didn’t break through the chines. I thunk up a quick and dirty little ply and pencil template to mark my lines for screwing into the chine logs. It worked like a charm.

100_6974 100_6973 The lower edge of the ply is held against the side panel. It follows the side curve and quickly scribes the screw line.

Gluing the bottom went well and was done in three sections. I was a bit dirty on myself for making the epoxy mixture a tad too runny, so that the squeeze out ran down the sides. By the time I had finished screwing it down the epoxy had gone off too much to make cleaning up easy. I was in panic mode at this point but managed to clean up most of the bits that will be visible, but I have a little bit of sanding to do. It will not be pretty looking into the hatches though!


The next morning (a late and relaxed 9.30am start!) I planed down the edges of the bottom ply to within about 3mm of the sides and also removed all the temporary screws before turning the hull over. The Goat is dead easy to turn single handed because it is so light. It can even stand on its side while unsupported, so you can walk around to the other side and lower it down. This boat has hidden talents!

Leaving about 3mm of the bottom edge protruding for now will give the chine some protection when turning the hull, as I do this with the roll method mentioned above.


Checking the hull is square. It’s perfect :)


I was extremely happy and satisfied with the fairness of the chines which really was all due to the extra care I took when planing the chine log bevels and the bulkhead bottoms. Seeing this part of the build turn out so well has been the highlight so far.

100_6835Time then for something a little exotic to celebrate! A cold one of these went down so nicely at lunch time.

I spent in the afternoon fitting and gluing the centre case. Up until now I’d not fitted the cleats to the top of the casing as I was tossing up whether to go with the Paulownia or Hoop pine cleats. I decided on the Paulownia, so these were installed as well as the bracing gusset.

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Well, that’s pretty much all I did. I had plenty of battle wounds to show, like dried epoxy stuck to me all over, including my hair. But I don’t care!

1 comment:

  1. Great tool for the bottom marking... I turned my bottom "upside down" to get the tracings so I could visualize the edge when placing the screws, but that meant I lost my centerline inside the boat to line up seat cleats, the trunk, etc. Very good idea, and similar to Clint's idea of a "jumpstick" for measuring the bulkhead notches.