Saturday, January 10, 2015

SEI progress. Slow, not very steady, but progress!

Progress in the boatshop.

 Bow on, I spent a little time researching this, and as a result hope that she shows a little of the Norwegian imagery that inspired her.
Shes fiberglassed up to the first lap joint, and in anticipation of a bit of hard use I fiberglassed  the inside of the lowest plank back about 1/4 of the boats length to provide impact strength should I sail into a deadhead or snag.
Yes I'll finish painting those shelves soon, I'd just put them up that day, cant have too many shelves and cupboards.
 Stern on, she's sharper forward than aft.
Those bundles are two sets of mast staves plus the gunwale strips.  All awaiting the cutting out of the worst knots and scarfing back together.
Stern view of the boats interior,  seams taped, seats rough fitted.  Note that the center thwart will sit down onto that frame. At this stage of the build I can very easily lift either end to waist height with one hand, I'd say she's about 90 lbs or so. No need for a diet there.

At a couple of hours every three or four days, SEI is taking longer than I like, but that’s all I can put into the project at present.  But she’s all planked up now, and I’m fitting the seat tops.
When I drew her, I tried to pinch the topsides a little in the midships area, the idea being to narrow the boat slightly to get better rowing geometry, but the planking did not want to lie fair so I let the top two planks spring out, and there are some “corrections” made to the framing after she was flipped over.
She’s a nice shape, to my eye at least.  I’ve drawn her finer forward and fatter aft than tradition would have it, but the area in which this boat will be used is notorious for short steep waves and I’ve drawn the boat this way to control her pitching when sailing to windward in these conditions.  That’s the theory anyway, I’ll be able to tell you how it works in a couple of months.

The job on hand right now is to cut the hatch openings into the seat tops then glue the doublers on underneath so the hatches can be properly fastened, then some sanding of the glass reinforcement on the seams so there are no spikes, then paint the inside of the tanks with epoxy and glue the seat tops on.

Those seat tops have to be airtight, they’re buoyancy tanks as well as places to put my behind, may have me standing on them at times, and any flex may break the seal and let water in /air out so this is a “do it right” operation.

Fitting the stern sheets, there will be a little brace under the forward end, that brace doubles as a footrest when rowing.

The other thing that’s happening is the mast. I’ve bought some cheap Baltic Spruce, full of pin knots, and the grain is a bit shaky but I figured that it’s fairly strong, quite light and comparatively cheap so its worth a try.  This will be a “birdsmouth” spar, 8 staves with a notch in one edge, so made that when they are put together they form a circle.  Glued together this system makes a nice light hollow mast, and in this case if I am careful to space the staves so the knots don’t coincide I expect that it will be strong enough.

For anyone interested, or wanting to build a spar this way, “Here” is a calculator which gives the angles and sizing for your spar. 

If you go to and search for “birdsmouth” you’ll get a whole lot of articles on making these masts.

 I ran a spare piece of knotty rejected wood to test the dimensions and section, heres the result, an 8 in long section that shows that the mast staves will produce what I want. The finished product of course will be rounded off, 65mm diameter, a hardwood section fitted inside where it goes through the mast step, same at the lower end and a lightweight plug goes in the top end.

I’m lazy, and prefer to do things the simple way so I use 8 staves which makes for a 45/45 angled notch which is only one setup on the sawbench, but it may be that a 6 stave spar is easier to assemble.  We’ll see in a day or two when I put this all together.

I’ve run the wood through the saw to make the staves, (thanks Blair for the help on that) and then made up a jig that held the staves against the saw table and fence while I ran them through to put the vee notches in one edge.  It took a little fiddling, but once set up I was able to run the 16 pieces for two masts, plus  4 spares through in less than half an hour.

 A rail to hold the batten across against the fence, and another above to hold it down solidly on the sawbench top, no slack, just a sliding fit. The saw blade was over at 45 deg, and when the batten was through it got end for ended and run through again which produced the vee section on one edge, the "birdsmouth".

The next job is to cut the biggest knots out, and scarf joint the pieces back together.  I have to do this with the gunwales as well and I’m expecting to have perhaps 20 scarf joints to make up, these in 16mm x 34mm pieces that are pretty flexible to handle.  So, another jig, this one a sliding “sledge” with a rail that fits the groove in the saw table (that’s what that groove is there for) and an angled fence and clamp that carries the piece through the saw blade at just the right angle.

Next, more jigs. These like little “goalposts”.  I don’t have a bench long enough to lay up these two masts, one 4.2m and one, the one for Blairs Saturday Night Special, at 4.5m so have made up a series of profiles on legs. These will be set up every 500 mm and lined up with the Makita laser level, and will provide a channel shaped assembly jig where I can lay each piece, coat the edge with glue and fit the next piece. 

I will be reinforcing the mast through the high load area of the  partners by fitting a fiberglass sleeve,  this material “here”   adds considerable strength to the wooden spar as well as preventing wear or abrasion damage where it comes out through the top partner ( mast step).  Its much easier to fit than trying to wrap the spar in cloth or tape, much stronger too. Good product.

I have in the past made hollow masts from two pieces and used a router with a ball end bit to hollow them out, then glued them together.  This  birdsmouth technique is much more fiddly, but I’ll hold the verdict until I have the two masts built.

Right now its 5 45 am, high tide in half an hour and I’m about to hop into the kayak and go upstream to watch the sun come up over the hill.


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