Thread: Building a Navigator yawl

Because the plans for bulkheads (and most parts) are given in 1:5 scale drawings, and because many of these bits are fabricated from several pieces, I found it wise and helpful to 'loft' these parts full sized and spaced against a large board 'centreline'. Assuming that the given dimensions are correct, this enables me to test the total and half widths before and after assembly of the components.

I know from setting the necks in musical instruments that a tiny change in the angle of a joint can become a large error when projected out along a long arm or 'lever', and even with the most careful clamping, these joints will creep a little given half a chance. The same drawings then enable the glued up bulkhead to be tested for width and position, and maybe 'carressed' or finessed into position before assembly. Even given all of that, the slots cut for stringers will need to be angled and adjusted to allow the stringers to take up a fair curve.



Here bulkhead 3 in the rough is tested against a centreline to make sure the widths are as designed.

Looks like you are indulging in a spot of 'real' boat-building with the lofting & etc Rob.
Will follow with interest. You've already done what would take me 6 months to do.
And incorporated a heap of cross-checking of dimensions in the process.
AJ

Originally Posted by b.o.a.t.

Looks like you are indulging in a spot of 'real' boat-building with the lofting & etc Rob.

AJ

Hi AJ, thanks. Not real lofting though, because the plans don't include a table of off-sets, you can only scale up the half-widths to full size. For beginners it would have been really useful to have full sized outlines of each bulkhead half width drawn with a common centreline, on a single sheet of paper. Never mind.



The transom doublers have been fitted oversized, and the transom skin has not got notches for the stringers. The doublers are left oversized to allow for the 'flare' of the hull going forward.
Look what I've done to my swept concrete floor already.

Wow, you're off to a flying start already. Making the transom doublers over-sized is a great idea, it'll save you a lot of epoxy filling those gaps later on. I'm really looking forward to see this build through to the end.

Good work!



Mick

Gawd, you're bringing back nightmares mate

Do you have one of them Japanese style razor saws? I bought one recently and was amazed at how it allowed you to shape and cut things like your stringer notches. In my case, it was fitting the side arms to the skiff and I found that not only was I able to cut right to a line, I could carve a thin sliver or wedge off the bit to make it fit - sometimes really fine stuff that you'd norrmally do with sandpaper or a file. With all the notches you'll be fiddling with, I'd suggest a good razor saw could become your most beloved tool

Leaving bits oversized is a good trick too. I did it on the skiff in places, though you may find as you start final shaping that you're marking things out again and have other 'issues'. It's a bit of a two edged sword - I found it led to more mucking about but can't remember the exact problems now but I think you'll be more satisfied with the result than just leaving a gap and filling it with pox.

Richard

Helpful replies thanks Mick and Richard. I'm keeping an eye on your photo pages Mick, to find evidence of your recent progress- it must be close now.

Richard, it's funny, I've used Japanese saws but don't have one- I have a couple of lovely dovetail saws that have a fine kerf, so I've never sort of got around to buying the Japanese type. The pull action does make very good sense and I probably will if I see one when I'm in the mood to open the wallet.



Bulkhead 2 with doublers around hatches and under deck. I have two hatches, one each side of centre because in the Yawl rig the mast is stepped aft of this bulkhead and a central hatch would be obscured by the mast.

Here the central lamination of the stem has been drawn up and is being shaped. A thin very flexible batten was used to fair the curves between John's co-ordinates on the drawing. This stem is an interesting shape; neither plumb nor particularly raked and he shows it with a couple of mm 'lean back' in the top 80mm or so. I cut it as drawn.
This central lamination will be used as a template to shape the two doublers.

#
The three laminations are temp screwed together and the one closest is being taken down to the template's shape. The straight bit with bearing is visible in the router. Didn't bother to plug in the big router for this job, the little cordless is up to a job of this size if the batteries are full.

Man I'll have to get a move on you will have yours finished before I even start.

Nice timmer BTW

You mean Coquina? You wouldn't want to hurry that...

Originally Posted by m2c1Iw

Man I'll have to get a move on you will have yours finished before I even start.

Nice timmer BTW

But you're not building one, you're building Coquina

It's not obvious in the photo Rob, so am I right in assuming you've got your router set so the guide bearing runs up the middle sheet while just cutting the outer?

Neat solution to the problem, much better than gluing the three together and then trying to shape them all to a pencil line.

I really like my trimmer router (mine has a tail ie, not cordless), there are so many jobs you can do with them ... and they cut fantastic holes for inspection ports.

Richard

Yep, although I have the two doublers on the near side of the 'central' ie longer lamination so that the template is furthest from the router, where the bearing is, and they were cut together.

(and I confess to cutting the inspection ports on B3 with a jig saw, very roughly because the router was set up for something else at the time. But of course that unspeakable roughness will be hidden by the ports...)

Originally Posted by rob540

Yep, although I have the two doublers on the near side of the 'central' ie longer lamination so that the template is furthest from the router, where the bearing is, and they were cut together.

Ahh, that explains why the bit looked so long.
Still reckon it beats doing it by hand.
You'd be amazed how many bits I managed to round off using my router (and this from a man who loves using hand tools )

unspeakable roughness will be hidden by the ports...)

They also hide where the router went astray while cutting 'neat' ones

Richard

Originally Posted by Daddles

You'd be amazed how many bits I managed to round off using my router (and this from a man who loves using hand tools )

Richard

Absolutely. A little round-over bit dresses edges so beautifully.

Geeeze, you're making all of us look bad. Its good too see that you are off to a flying start. If you haven't already done so, join the John Welsford Yahoo group. Not only are there plenty of pictures available, but there is a fairly large community of people all happy to answer your questions.


Cheers

Mickj


PS - I'll upload some more pcitures of my Nav this weekend.