Thread: Tom Cat

Yup. If it was on a mooring in salt water I'd be a bit concerned about the reaction between graphite and stainless. Dry-sailed, and mainly in fresh, is not so much of a worry.

I'd still be inclined to check it every so often. Even though the graphite is supposedly "entombed" in epoxy, any bearing which has a given percentage of graphite in the mix will still have the same percentage of graphite exposed at any surface. If the mix is 70% epoxy and 30% graphite (just as an example) then any hole bored through it will have a surface that is 70% epoxy and 30% exposed graphite.

Same applies to silica in the mix. The amount exposed in any hole bored through the mix will be directly related to the percentage in the mix. It's just another surface, so you can use the analogy of silica fillets being harder to sand.

Anyway, minor concerns for a boat like this. I just thought it was worth mentioning, mainly in case other people were tempted to use the same idea on different boats.

Who would have thought so much brain power was needed to sort out a few boards - certainly caught me by surprise! The first hurdle was the difference in grain and colour in the timber once it was ripped and planed. Holy cow! Spent ages just trying to figure out just how I was going to cut them up and attempt to get them to look OK. I’m not saying I don’t like the timber, just the fact that they were so different! Much time was spent before I started cutting them up but all in all there they are. I might consider looking at staining but I’d prefer not.

The next thing was the decision about how to lay them – with a 3mm gap, a 6mm gap or no gap! More muckin’ about with fiddly bits of ply and fibre board pieces, just like the Floor Boards. I have attempted to show this in the pics with comments. I finally decided on matching the gaps with the Floor Boards ie. 6mm. You might also notice that the boards have been swapped around for colour co-ordination. I have left you with the puzzle! However, unfortunately, there are no prizes for the winner. I think I got it the best I could.

Onwards from here to completing the final piece - had to wait for the final gap decision to get its width. Once done the easy part finally arrives of cutting to length, routing in the chamfer and generally making them look like they belong.

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On the point of the graphite mix - I took this idea from the “The Gougeon Brothers on Boat Construction” book. This is an absolute tome for all aficionados using epoxy construction techniques for building their boats (in my case anyway). In this area they do mention dry sailed boats only and don’t specifically talk about CB Pins but do mention bearing surfaces.
Quote “423 Graphite Powder is a fine black powder that can be mixed with WEST SYSTEM epoxy to produce a low friction exterior coating with increased scuff resistance and durability. Epoxy/graphite is commonly used as a bearing surface and as a coating on rudders and centreboards or the bottoms of racing craft that are dry sailed”.

I took the “bearing surface” to be a fairly common way of improving the wear characteristics of the CB Pin /Hole sceanrio so it appears I may have misread the intent of this little piece of info. Thanks for the heads up on this. The pin is very easy to get at so I take the offered advice willingly and ensure it’s checked regularly – once I get the thing finished that is!!

As an aside I took an opportunity recently to replace the SS CB Pin with a silicon bronze one – dunno if that’s better or worse but I am attempting to have all my fixings, fixtures and fittings in SB for this build.

Looks fine, and the timber colours will mellow out with time anyway, so the difference wont be so noticeable in a couple of years.

The Seat framing is finally all done. After I stuck my bum on a few boards I realized that I would need further support structure so have added a member to the side seats and an athwartships member in front of the transom. This particular one is made of Tas Oak and am hoping that because of its inherent strength will not need to provide a vertical support in the middle. I have also shared a pic that shows the joint method that I have used on the side supports. I picked this up from the Gougheon Bros book…a typical epoxy joint but also one that is easily fabricated. A couple of saw cuts, a bit of chisel work and you’re done.

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Now just need to fix everything in place but will contemplate varnishing them first so next steps…

• Install the big Breasthook
• Install the Quarter Knees
• Move onto the fabrication of the Coaming Supports

My intention now is to complete the fitting of the Coaming Supports but not to fix them in place until I have painted the interior. I can be finishing the Seat Support components whilst all the other is happening then once the interior paintwork is done I can install them, give them a couple more coats and get on with completing the Seat Boards themselves.
I think this will give me just the undersides of everything to paint when the deck etc goes on. Planning is wonderful, isn’t it? Leaves plenty of room for amendment!!!

That joint is the proper way to join perpendiculars such as the deck beams to the sheer clamp, carlins to deck opening framing , etc. The idea is to offer more faying surface for glue, spread loads over a larger area and most importantly, not trap moisture within it, in the event of a leak. The joint's slope will self drain, preventing rot from getting a toe hold inside the joint. Wonderful work as usual.

Time moves on…boat construction moves on (albeit with documentation in its scarcity).

• I have installed the big Breasthook but have left the shaping until later.
• Installation of the Quarter Knees has been delayed until such time as interior paint and then Seats are installed.
• I have moved on to the fwd Coaming Supports.

The fwd Coaming Supports (Chocks to Bill G – what the hell!) have been completed in two parts as per plan starting with an outer of 150mm wide (6” for Yanks). The same dimensional accuracy cannot be said of the thickness.

A little story here…I scoured the drawings for the thickness of these bits but only came up with the Aft Coaming Support thickness of 38mm (1 ½”). Considering the Sheer has a bit of curve and that I had 25mm (1”) timber I reckoned on installing the 25mm (1”) initially as this thickness would be easier to spring into position and then subsequently gluing the added thickness of 12mm (1/2”) after the event. Accordingly I painstakingly dry fitted the Pt and Stbd bits after taking a pattern from them for later use on the thinner stock. All going to plan so far! I epoxyed them in, cleaned up as best I could and left the shed to return the following day. However, it still niggled me about the thickness dimension of the Fwd Coaming Supports. I had copied all the drawings from Bill’s book onto large drafting paper and pinned them up in the shed so I wouldn’t need the book there. Once in the house I pulled out the book and grabbed a magnifying glass to scour the drawings just once more. I figured the print in the book would be more defined then what the hugely blown up drawings would be in the shed and sure enough it took some time but Bill had put it in there. One of those quirky things…considering the Aft Coaming Support was 38mm (1 ½”) on the drawing I went looking for a 38mm (1 ½”) dimension on the Fwd Coaming Supports and couldn’t find it. I felt vindicated but hang on!!!...what’s that little dimension of 19mm (¾”) tucked in between two of the cabin curve dimensions on the Construction plan view? Bloody hell!! On the blown up drawing this was nothing more than a couple of lines with an unintelligible blob on the end! Bill’s done me in .

However, all is not lost…after some head scratching I figure this thinner dimension was created to account for the curvature of the Sheer and I also figure that after I have shaped the deck camber into that 25mm (1”) piece of wood I would end up with about 19mm (¾”) at its thinnest point. But that doesn’t account for the Aft Coaming Supports being 38mm (1 ½”). More head scratching and my answer is thus…there are no rear Quarter Knees of 38mm (1 ½”) to match the Breasthook and I figure these may have been replaced in the design by the thick rear Coaming Supports. Even though they are a little fwd of the Transom these rear Supports would provide a similar reinforcement in the stern area. For those following my thread you will note that I had manufactured Quarter Knees (at 38mm -1 ½” mind you!) for use to bolt the increased width main sheet Horse to so now I figure, I have some scope in the design of the rear Coaming Supports considering I have the thick Quarter Knees. Lo and behold I have more 25mm (1”) thick timber and guess what my rear Coaming Support thickness will be?

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All in all not a bad result – even thickness Coaming Supports fore and aft .

The temperature in my part of the world has fallen considerably and without some kind of heating in the shed the painting has been put on the back burner (no pun intended!).

Looking at what is coming up I have turned my attention to the Aft Coaming Chocks as a means to continue. At least I can ready the parts for assembly when required.
I was lucky enough to have retained a thick cardboard carton that a purchased filing cabinet came in so have been using that to make templates when required. This area is one of those times so taking the plans drawing, copied dimensions provided onto the cardboard and proceeded to create a template that will fill the bill.

One of the traps in this particular exercise is ensuring enough timber is available to create the 75/300mm (3”/ft) slope required for the Coaming and yet retain the original dimension at finished deck level. Using the bandsaw with the table sloped correctly and then cutting to the line on the opposite Support just may bring everything undone! A good time to mark the top side on the wood! Also one of the advantages of the template is that it can be adjusted back and forth until such time as you’re satisfied you have it right noting all the time that the Aft sections need to meet up with the Fwd sections. The aim of course is a nice even curve the entire distance of the Coaming from centre Fwd to centre Aft.

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I have realized that I won’t get away with 25mm thickness due to the camber of the deck and the curve of the sheer. The combination of these two conflicting curves does not leave enough thickness for the job of attaching the Coaming. Out with the trusty 12mm marine ply left overs and laminate on. I love that polyurethane glue – simple to use and easy to clean up - wet or dry. I have now put these aside as I start thinking about the paint.

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Hmmm...dilemma. Should I opt for International Toplac (the paint of choice so far) or go for the 2 pack job – International Perfection? I pondered this for some time, then after a period, was swayed towards Perfection because of the knowledge that it would stand up longer. It was a bit of an opposite type of thinking as most would 2 pack the bottom and topsides of a trailerable boat and use single pack on the interior. Not one to take the easy road my laziness pushed me fully to the 2 pack for the interior knowing it has superior scuff resistant qualities etc. and with luck would last far longer before needing a refurb. Also my experience shows that a boat on a trailer has a propensity to sit full of water in the back yard!

I bit the bullet and went for it. Although not absolutely necessary, as my interior had been sheathed in glass/epoxy, I opted to apply a couple of coats of Perfection Undercoat (PU) initially to build up the coating. My plan was to apply all coats without any sanding except for the glass/epoxy base so the recoat times were crucial to success. The weather was against me all the way as the temperatures were consistently between 10 – 15 degreesC throughout the painting period. So I commenced work and it went something like this…

• Apply intial PU undercoat
• Apply second coat 2 days later
• Ponder the fact that I may not get 2 top coats out of my 1 x 750ml tin of Mediterranean White and considering I had 2 coats of undercoat on and curing, time was short. The only available colour at short notice was Snow White at BFC in Toowoomba so I opted for that as the initial finish coat.
• Apply initial coat of Perfection (Snow White)

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Apply final coat of Perfection (Mediterranean White)

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You be the judge.
Would I do that again? Nope! I would stick with the Toplac for the interior.

I agree in the choice of a single part polyurethane, instead of the 2 pack you employed. Just not worth the bother on the inside and especially on a traditional, classic like yours. It looks good, as usual.

Might have been a complete PITA to apply, but it certainly looks good.
I have family in Toowoomba. I'd better get them to look you up in prep for launching.

I couldn’t have picked a worse time of the year for this work! I have chosen Feast Watson (FW) Exterior Varnish Satin for the varnish work but to start I have given everything a coat of FW Timber Primer. This is a penetrating wood preserver and primes new timber prior to applying the varnish. Timber Primer has added water repellent attributes and inhibits mould growth (so the blurb goes). Good enough for me and a boat that will sit on a trailer most of its life.

But first I needed to finish the Seat Boards ready for this stuff. They have been finished off with some curves and routed edges. Having given some more thought on how I should finish the edges I decided to rout top and bottom edges – this should provide rolled edges on top to give backsides no grief and the same rolled edges on the bottom to provide continuous edges for the varnish so we don’t have premature peeling of the finish at the juncture of the edges.

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I ended giving everything 2 coats of Timber Primer and I have just finished giving the Seat Supports 3 coats of varnish. Next job is to install the Seat Supports to make room on my benches to varnish the Seat Boards. The weather isn’t the best for this type of work but its moving forward albeit slowly as the temperature is friendly one day and not the next etc.
In between each coat I am using synthetic steel wool or ordinary kitchen scouring pads to rough the surface - pricing for these is much of a muchness and appear to give the same result. After each session of this I clean in water and Metho ready for the next coat. The Rosewood has a very open grain but I like it and the presentation it gives.

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Hello Laurie! Nice progress! Can you advise what width you made the mast step please?

Hi Greg - great to hear from you and assume things are proceeding. I don't see much on your thread - more, more please!!
Anyway, to the question at hand...as per the plans 1 1/2". However, not to question Bill's design too much, I felt uncomfortable with this skinny little bit bearing the side forces of a mast that has no shrouds so for my own piece of mind I epoxied a piece of 5 ply 1/2" thick to either side. Also let it protrude approx. 1/2" down each side of the Step onto the Stem just to give that little more security. Whether it makes any difference or not I'll most probably never know!

The Step is installed with two large SB Screws thru the Stem, one forward and one down aft, as well as copious amounts of epoxy. You could use bolts instead but...........

Also if following my method, be wary of the gap required for cleaning and drainage between the edges of the extra wood and the planking. Best to do some mock ups with some cardboard or such before committing to the extra thickness in this area.

Please refer this thread #57 Pic 7 - you can just see the overlap onto the Stem. Also refer #59 Pic 1 - you can see the ply edges on either side.