Kotik, Kotik, Kotik!

[OliverBendix]

Kia ora Ian,
Just checking in to say that I'm watching with interest - both watching the construction and admiring your workspace! I'd call Dunedin one of my home towns and the availability of cheapish space sometimes tempts me to move back south... Otago harbour is also a lovely place for small boats, though tricky for big ones.
Oliver Thompson.

[skaraborgcraft]

Ian, i think if i was going to glue them,whether with epoxy or rescourcinal, i would probably run them through the saw again into thinner bits (would help with drying too). But if you are happy with the movement you might get in wet/dry cycles of timber that thick, i would probably consider bedding using a polysulphide. Your drifts and fastenings through the keel should be keeping it all together, regardless if glued or not. It would seem that 2in thick would be regarded by many to be the thickest timber used in epoxy lamination, as timber of greater thickness can swell breaking even an epoxy joint. Ian.

[IanMilne]

Thanks for all the thoughtful suggestions, Peter, Andrew and Ian. Yes, I can get resorcinol here. It's very expensive, but that's not the point, is it. WEST G-flex would seem to be suitable, but it only comes in small packs. 3M 5200 or something equally tenacious would be a good bedding. I used something like that to bed the ballast of my EM, but I forget what brand it was. And as you say Ian, to cut the pieces thinner would be a sensible idea, to help them dry, but that would use more glue. I was told they wouldn't move now. Iain's plan shows the deadwood in 3" (75mm) layers, but of course you just build it up any way you can. A polyurethane glue would handle the dampness (e.g., Gorilla, Fixit Mate). I know the moisture content for epoxy should be 12-14%. Is that on the surface or right through? Whatever I decide, I won't hold you responsible.

Oliver, Kia ora. Welcome aboard, as Andrew said to me recently. Wellington was my home town until I was about 20, a long time ago. I have many good memories of it, and I still enjoy going back there now and then, especially on the Cook Strait ferry. Wellington Harbour would be great to sail on.

Cheers, Ian

[skaraborgcraft]

If you are happy glueing lams that thick Ian,then go for it, it will be interesting to see how it holds up. Obviousy every bit of timber is different, so swell and shrinkage can only be estimated, but the glue joint is only half the issue, as bigger timber may also open up elsewhere. If you are considering sheathing the underwater area, then i would be happy to go with what you have. I usually go with surface moisture content, as that is what the glue is trying to bond to, the tips of my meter go further into the wood than any epoxy will penetrate. I have only seen bond failures on unprepared teak with a polyurethane glue, and i use a lot of it due to working conditions, low tempertures and sometimes a need to get the job done "today", and in all my own tests, the wood has always failed first.

[IanMilne]

Hi guys,
Thanks for all that good advice. After all that, and much cogitating, I have decided to abandon the oak for the forefoot and deadwood, not only for the gluing question but also for its moisture content and its weight under the stern, with us in the cockpit and the o/b motor under the after deck. (It's not "green", but the moisture content is still above 14% in most parts.) I will probably use macrocarpa instead, with a shoe of kwila along the bottom edge. The oak will be good for smaller parts later on.

Now for a quick update. It's all standard stuff, really.

Lifting the bevels off the lofting (stations and waterlines):


Making saw-cuts to the marks.


Saw-cuts notched out to make them easier to see.


The stem. (That's DWL, upside down.)


Fairing the keelson.


All faired up.


Now, Let the Planking Begin!

Cheers,
Ian

[andrewpatrol]

Geez you got through that arduous stage pretty quick Ian, good on ya. Do you fit the centre case now or after planking?

[IanHowick]

Hi Ian,

I just realised we had another connection (other than first name) going back nearly 30 years:


I recognise that kayak in the roof with the high stern. A friend and I bought a fibreglass version of that from someone in Dunedin in 1987 or 1988 and paddled down to Port Pegasus, Stewart Island that summer. I'm guessing that is the original SOF kayak, you made a ply stitch and glue version from it, then you or someone must have made a fibreglass mould and then some fibreglass versions.

[IanMilne]

Thanks, Andrew. The fairing was pretty straightforward really, but I had to keep sharpening my planes for that laminated kwila. Now I am sort of working on the c/case and garboards together. They are both out of the same two sheets of 12mm ply.

Hi Ian, Yes, after I had built the yellow kayak and a couple of stitch and tape versions of it, Craig Kennedy asked me if he could make a mould of it, so I let him have a copy of the lines and he and his friends built five fibreglass ones. I never saw them, until Alison and I discovered one at Whakatahuri in Pelorus Sound on our six week Eun na Mara trip in January and February 2012. I thought those guys had made a good job of it. I'm pleased to hear that one of them got as far south as Port Pegasus. That's pretty far south! (That's down the east coast of Stewart Island, you guys.) I took my plywood one to Doubtful Sound twice, and Dusky Sound twice, and my son Andrew also took it to Dusky Sound with some friends of his. My second trip there was also with Andrew. He had another kayak then. That was in 1996, my last kayak camping trip, a good one to remember my kayaking by.


Cheers,
Ian

[IanHowick]

Hi Ian, Yes, after I had built the yellow kayak and a couple of stitch and tape versions of it, Craig Kennedy asked me if he could make a mould of it, so I let him have a copy of the lines and he and his friends built five fibreglass ones. I never saw them, until Alison and I discovered one at Whakatahuri in Pelorus Sound on our six week Eun na Mara trip in January and February 2012. I thought those guys had made a good job of it. I'm pleased to hear that one of them got as far south as Port Pegasus. That's pretty far south! (That's down the east coast of Stewart Island, you guys.) I took my plywood one to Doubtful Sound twice, and Dusky Sound twice, and my son Andrew also took it to Dusky Sound with some friends of his. My second trip there was also with Andrew. He had another kayak then. That was in 1996, my last kayak camping trip, a good one to remember my kayaking by.


Cheers,
Ian

Interesting, that may be the kayak we paddled down to Pegasus, it's the right colour and the fellow I paddled with and who ended up with it subsequently moved to Nelson. I also paddled it down the Hollyford River to Martins Bay. Storm conditions came up overnight and lasted for a week after we got to Martins Bay, so we gave up on paddling out and down to Milford Sound and flew out with a kayak tied to each skid of a Hughie 300 helicopter.

Ian

[IanMilne]

Yes, there were some great trips done in those days, weren't there. Maybe there still are - I'm out of touch with it now. We flew in to Dusky Sound and out again with the kayaks lashed to the floats of the 'plane. Something to talk about next time we meet....

I got my Kotik starboard garboard shaped up today. Now I can use it as a pattern for the port one. Then the centrecase.

[andrewpatrol]

Which method do you use for template to get your planks Ian. I tried spiling both sides onto a dummy plank but could not get it close enough. So I ended up with a rough spile then cutting it over size and sneaking up on it for bottom edge then place on boat and transfer top edge from marks on frames taken from I.O. Plank layout. All the while following the "fair lines rule" mantra.

[skaraborgcraft]

Going great Ian. What kind of plywood have you got?

[IanMilne]

Hi Andrew,

For the Eun na Mara, I tried various methods, ending up with complete patterns out of thin rubbishy plywood, and then dividing them into three parts according to where I wanted the scarfs to be. For the Sooty Tern I used strips of that plywood as spiling battens with the compass arc method, as best explained in "The Dory Book" by John Gardner, with Sam Manning's brilliant drawings, and then made complete patterns out of 3mm MDF, which I kept. (I've still got the moulds too.) For Kotik, I am using the ST plank patterns as spiling battens. The two hulls are similar in style, so that works quite well.

I had kept the patterns in their three pieces, so I reassembled them with hot melt glue. For the garboard I laid the ST garboard pattern along the moulds, approximately amidships, lapping onto the edge of the keelson, with its station 5 mark at Stn 5, and marked the other stations with lines right across it, then measured the distances in millimetres along the extended lines from the edge of the pattern to the Kotik centreline and to the plank marks on each mould, and wrote them on it. I ran a batten around the planking land marks to get the distances between stations. You can also draw lines at any angle you like and measure the distance to extend them to any point you want to reproduce, so I did that at the ends. This system probably has a short name.

Then I took the patterns apart again and laid them out on the plywood as economically as I could by measuring out the required distance along each extended station line, allowing a bit extra all around, marked the points with thin nails, joined them up with battens and drew the shapes. Then I cut them out with my jigsaw, a bit oversize, and tried them on the moulds, clamped in place and overlapping 100mm where the scarfs will be. Then I spent another couple of hours improving the fairing of the keelson and creeping up on the fit of the planks, on the "fair lines" principle, like you did. When they all fitted I turned them over onto the port side of the moulds and they fitted there too, so then I drew around them again onto the plywood for the matching set. That's how they are right now. I will use the compass arc method for the rest, as much as possible.

I had marked out the middle section of the first plank on one sheet of 12mm plywood and the two end pieces on the other sheet with the centre-case sides. Then I got all of the second plank out of the first piece of plywood. I will also get the cockpit sole out of what's left, but it will need a join in it.

Thanks, Skara. The plywood is meranti, BS 1088, made in Indonesia. It is 12mm 7-ply, with four thin lengthwise layers and three thicker crosswise layers. It is the best I could get, but I preferred the 12mm 9-ply I had for the EM. I have also got 7 sheets of meranti 9mm 5-ply from the same supplier, and 7 sheets of okoume 9mm 5-ply, BS 1088, made in Malaysia, from a different supplier. I will use the meranti for the hull and the okoume for the rest, but I don't know if the okoume will look good varnished. Finding good plywood was difficult.

Because the hull has very rounded end profiles, there is not a lot of twist in the garboards at the ends.

Ian

[IanMilne]

The planking begins. First I checked the lands with a long batten.


Next I used the Sooty Tern garboard pattern to spile the Kotik garboard,


I thought the bow part of it looked a bit peculiar so I checked it with a piece of wallpaper.
This is the second garboard being marked out from the first one. The end pieces came from the other sheet of plywood, along with the centrecase sides.


I fitted struts across moulds 4, 5 and 6 at the right height to support the centrecase,

cut out the openings, and made a dry assembly of the centrecase parts. The outer log is made from two pieces of that kwila house-decking, with the grooves facing into each other.


To be continued:

[IanMilne]

I glued the two layers of the outer log together, but not to the frame.

When I had cleaned it up, I faired it to the frames and keelson. I will take it out to install the centrecase. It's a bit of a juggling act at the moment.


Trying the garboard in place, before I had scarfed it.


Scarfing in progress.


Checking the fit and alignment of the scarfs.


Centrecase sides, glassed, with three coats of epoxy and two coats of primer so far. Two or three coats of anti-fouling to come.

[IanMilne]

I have been spending some time learning how to cut threads on the rods for the keel and deadwood bolts, on my father's old lathe. (That's it, under the blue cover.) I've done the 3/8" copper ones now, but the nominal 5/8" (actually nearer 3/4") aluminium-bronze is too thick for it, so I will have to get them done for me. Anyway, I understand the lathe much better now. It's a 1940s Myford 3 1/2" (that's a 7" swing in American).

Here we go with some more piccies.
I fitted the garboards dry, and cut the slot from underneath with my "multi-tool" saw and pull-saw.


Then I glued the centreboard case to the keelson. I couldn't get any screws in. It is resting on the struts across the moulds. After that, I glued the outer log to the case, and to the frame at station 5. It does not reach frames 4 and 6 as bulkheads have to go in between, later. The clamps dented the anti-fouling paint, even though it had been on for several days.


I glued the scarfs "on the boat". This is the way I have done them for my other boats, but I will try gluing the next one on the bench.


At the stems, I cut a 3mm step to allow for the extra thickness of the garboards. This is shown in Iain O's clinker manual, item 4.30. (This garboard is a complete contrast to Max's Cape Henry 21. I have no doubt as to which will be the faster boat.)


Stern view of garboards.


I've cleaned up the squeeze-out underneath, and will trim the centrecase flush with the planking before I plane the flat along the centreline.


Now I will go and take all those screws out, using the old soldering iron trick.
Ian

[andrewpatrol]

Doing well Ian. If I can persuade you one or the other, I did all my planks scarfed on the bench and wouldn't hesitate to do it that way again, only its maybe good to have an extra set of hands when putting plank on boat with the goop everywhere, but I would imagine you know all this having built a few boats in your time. Helps heaps getting a fair line on the whole plank and scarfs come out pretty good, well some of mine did.
what thickness of ply is rest of the boat?

[IanMilne]

Thanks for that, Andrew. Yes, I think you're right. Gluing the scarfs on the bench will give better control of the whole thing. Glue the scarfs one day, hang the plank the next. I do have an extra pair of hands around here too. I also use hook-shaped plywood brackets clamped to a couple of the moulds to hang the plank in while I get it positioned right. I will also leave some extra length on the ends of each plank until after I have hung it. I forgot to do that with these garboards until it was too late. They are very pointy at the ends.
The garboard is 12mm, the rest are 9mm.
I trimmed the centrecase and planed the flat along the centreline today.

[IanMilne]

Since my last posting we heard that our new boat-trailer was almost ready, so I got to work making the pattern for the lead ballast, which the local foundry will use to make a sand mould. The pattern is made from 1" (25mm) cheap pine boards, plastered smooth and painted. Then I made a jig to hold the keel bolts in the correct positions, which took a bit of evolving. This will be carefully positioned over the sand mould and the lead poured in around them. The idea is to get the casting done and put straight onto the trailer, and then turn the hull over onto the ballast, later. We will be ready when the trailer is.

We have just had our long Labour Weekend away with our Sooty Tern Trondra.

The white thing is the pattern, which in these two pictures represents one side of the open mould.




Oversized holes for the keel bolts, staggered.


Do they fit? Yes!




The blocks are made to the same height as the floors will be. I have adjusted the heights of the bolts slightly since this photo was taken.



EDIT, 5 November 2018. When I made the pattern, I made it the same length and with the keel bolts at the spacing shown on the plans. I did not allow for contraction of the lead on cooling. After further thought I added 20mm (3/4") to the length of the pattern, but did not change the bolt spacing. The completed casting was difficult to fit the boat when we turned her over. The overall length was right but the bolts were slightly too close together, so I had to spend some time adjusting to holes in the keelson. The correct thing to have done with the keel bolts in the jig would have been to space them out in the jig at the same percentages of the total length of the extended pattern, in relation to the ends and each other. I hope that's clear enough.

[andrewpatrol]

Those bolts are massive Ian, your ballast ain't goin nowhere. Good idea putting it on the trailer too, the number of times I had to move mine. Will you take the boat off trailer after bolting on the lead?

[IanMilne]

Hi Andrew, We decided to upgrade the bolts from 12mm to 16mm (1/2" to 5/8"), so I ordered 5/8" (it's sold in imperial) but when it came it was nearer 3/4. Then I found that they leave a "machining allowance" (which means that you have to machine it) so my brother and I just turned the ends down to 5/8" and cut the threads on that. He's the engineer, I'm not.
When the hull is built I will paint the bit where the lead goes the same as the rest, paint the sides and bottom of the lead while it is on the trailer, put the hull down on the sealant, and pour slightly thickened resin down around the bolts before I do them up. Then I will build the rest of the boat on the trailer.
I see you used Sika 291 as the sealant.
Cheers, Ian

[andrewpatrol]

Yes 291 it seems to have worked pretty well, but obviously time will tell! You have to be reasonably quick, more than they say on instructions cos I thought it seemed to skin over before I put things together but cos I put so much on it squeezed out alright...luckily. I also used their primers. Extra $ but........

[IanMilne]

Thanks for that. Sounds like you did a good job.

[skaraborgcraft]

Going really well Ian. Like those keel bolts. Always good to get the first bottom planks on.

[IanMilne]

It's been a bit slow going lately, but never mind. Here is some more progress.

I was fortunate to obtain a couple of nice big planks, or beams, of recycled NZ kauri (560 kg/m3) for the keel and deadwood. They are 70mm (2 3/4") thick, which is just right for my table-saw.


Here I have cut the taper on the longest piece. Now I am cutting the curve to fit the hull.


Trial fit. Not glued yet. It would have been slightly better not to have cut the taper yet.


Here's why. There is also a taper vertically. This is the cross-section at station 8.


Here are all the parts stacked up on the ballast pattern. I can glue it all onto the hull now, except for the last three pieces. The lowest piece is that oak I was talking about a while ago. Since this photo was taken I have glued the four middle pieces together and cleaned up the sides with planes and belt sander.


Here's a view of the whole thing. It has taken a lot of trial fitting and trimming. It's all just sitting there so far. The forefoot is oak, too.

My wallpaper pattern of all this, traced off the lofting, was very useful. I redivided it according to the thickness of this timber, so then I had a pattern for each piece.

We also got our new boat trailer last week. I'll post a picture of that next time.

Cheers, Ian

[PeterSibley]

That kauri was a great score !!!

[andrewpatrol]

So Kauri would be about the same weight as Douglas Fir? Geez I envy you not having the board through the ballast. It's a real pain in the ....

[IanMilne]

Thanks, guys. Yes, the kauri is very nice to work with. According to my book, "New Zealand Timbers - The complete guide to exotic and indigenous woods", by Norman Clifton, 1991, the density of old growth Canadian Douglas fir is 530 kg/m3.
I like the idea of the off-set centreboard too. It makes the ballast much simpler and it will keep the slot clear of the mud and sand if we go aground at night like we used to do on some of our trips. I will need to make beaching legs for that though, which is another story...

[IanMilne]

Here's the trailer. It was designed for the boat and can adjusted to fit. I got a tandem because there is a popular New Zealand trailer-sailer called a Noelex 25 which has the same design displacement, 1180kg, and they all have tandem trailers.


Here's the glue-up. I have used the two step system on this - priming the surfaces with straight resin, then putting the thickened mix on, also on both surfaces to get enough gap-filling. Yay for epoxy!


When this much was glued up and set, I marked the stern-post line and cut it with a hand saw.


I tested the various theories about gluing oak. I sanded the pieces of oak first with 40-grit paper, then wiped #1 with methylated spirits with a couple of lumps of bicarbonate of soda (mild alkaline) in it to neutralise the reputed acidity of the oak, #2 with straight meths, #3 with acetone and #4 with nothing. Then I glued a piece of kauri to each one and left them for a couple of days. When I tried to chisel them apart, they all came out the same. The kauri broke, not the glue.


So I glued the oak "shoes" onto the deadwood and forefoot. I sanded them with 40 grit, then just wiped them with meths to get the dust off. It evaporated while I mixed the resin.


I also installed the four vertical 3/8" copper rods in the deadwood. I had drilled the holes in each piece as I made it, then completed the job by running a 400mm (16") drill up through the whole thing, and recessing the tops for the nuts with a brace and bit. I put small corks in the bottom of each hole and filled them with epoxy, then I used a long piece of wire down the hole to push the cork out and immediately pushed the rod into the hole from underneath and hammered it (not too hard) up through, so that any irregularities in the holes got filled with epoxy. Then I put the top washer and nut on and tightened up both ends. This is how it looks now.


Now, about that planking....

[skaraborgcraft]

Nice going Ian. 40 grit and a wipe with acetone is pretty much what i do with any timber. Nice trailer!

[IanMilne]

Thanks, Skara. That's good, then.
Ian

[andrewpatrol]

good to see you have a full head of steam up again Ian. fun handling a great lump of keel isnt it? Could you take a pic of trailer from the back so I can see the setup of rollers please.

[PeterSibley]

good to see you have a full head of steam up again Ian. fun handling a great lump of keel isnt it? Could you take a pic of trailer from the back so I can see the setup of rollers please.

Yes please.

[Zuri]

Following along with interest. You're coming right along with this.

Will the casting from the factory be about the same size as your pattern or do you have to make it a certain percentage bigger to allow for shrinkage?

Travis.

[IanMilne]

Here are some more trailer photos, Andrew, and Peter. The Kotik has a straight keel but the Grey Seal keel has some rocker, so the GS trailer will have to be more like my Sooty Tern trailer in that respect.

This shows the guide-wheels we had fitted to our Eun na Mara trailer after we had been using it for a while.


This is my Sooty Tern trailer, showing individually adjusted rollers. (The plank was part of the mould for casting the Eun na Mara ballast.)


Our new Kotik trailer, with guide-wheels and side posts. The various parts will be adjusted to fit the hull. I plan to put the hull straight onto the trailer when I turn it over.


The port side guide-wheels might have to be altered, as the centreboard comes fairly well down the side of the ballast, even when it is up.


This shows how the "wobbly-wheels" are adjustable for height and angle. They will probably be fixed in place when the right position is found.


This shows the centering system, which includes the side posts, at the back of the trailer. The blue rollers are standard fittings.


We have a very good trailer maker. Any more questions - feel free.

The next post will be planking, planking!

Cheers, Ian