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159 Mast Support Trailering
The holiday season is over once again so I’m back at my favorite on-line past time.
To better understand and appreciate what I’m getting myself into with regards a bird’s mouth main mast I decided that I would fabricate the mast support for trailering using this methodology. The idea being to utilize the existing Mast Step and Deck Support in the boat and fabricate the bottom 1200mm or so of the Mast to create a support for trailering.
So, as usual, I neglected to take pics from the ‘get go’ so apologies before I begin! My bible for mast fabrication is an article written by Gaetan Jette titled Bird’s Mouth Spars Revisited and can be found in Bird's Mouth Spars revisited. My suggestion is to read and digest this great article if interested in these types of Spars!
The upshot for me is an 8 sided Mast with Staves 35 wide x 17 thick but complicated by the fact that in this area the circumference of the Spar goes from its majority diameter dimension of 89mm (3-1/2”) to 67mm (2-5/8”) with a slight curve over the length of the Support area - go figure! Oh well – good learning experience. To date I have cut, planed, cut the mitres and created the taper. The next job before I start throwing epoxy everywhere is to fabricate the in-fill piece to make it solid. Not looking forward to this bit so will sleep on it in an effort to come up with the most efficient way of doing it. The pics show how it has gone together so far……
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160 Mast Support Trailering Cont…
My trip to the Tasmanian Wooden Boat Festival was just great! Spent four days in Hobart without the better half so was able to concentrate to soak it all in without the usual distractions. If you have the chance, just do it. This was my third festival and I’m already hankering for 2019!
OK, back to the boat – the Mast Support is coming together…the plug was fabricated and fit. Must say it was a pretty average fit but considering its use I’m sure the extra epoxy used won’t make a hell of a difference. It’s all good training for the real thing! My methodology was to epoxy together two staves at a time to end up with four pieces to finally assemble around the plug.
It all went together really well and am on to the finishing stages. Planing is done - 8 sided, 16 sided and the take off the corners left. Now down to the glass paper – to that end I found a piece of pipe this morning that I will use to assist in this final rounding process by gluing the paper to the inside of a piece of half pipe. We'll see how that goes and once that has been completed I will cut a tenon in the small end to fit the Mast Step and fabricate a spar support for the top end. Stay tuned!
Glue up of the Core...........................Core 8 sided to fit
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Final glue up....................................Rounding commences
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Awaiting final sanding
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161 Mast Support Trailering Cont 1…
We’re getting there…but first answers to Greg’s questions.
a) The graph paper is metric - Aussie you know! Still can’t understand why the US population can’t get its international act together. It’s like you’re on another planet! Anyway, enough! The diameter of the hole is 4-1/2” giving a 1/2” gap all round (is that better?). My original intention was to insert about 8 tapered pegs to shore her up – the intention was for this larger hole to provide some play for insertion considering it was coming in and out every time I go sailing. However, I found that a piece of rubberized floor mat may be a better option then the pegs. It is as hard as nails but has that little bit of give whilst inserting and doesn’t move a fraction once in position. It can also be replaced at will. After much consideration and reflection I perceive Bill was providing a tapered hole for a tapered mast to fit into without any gaps. Just insert and it’s all over – drag her out when done.
b) The hole I have created doesn’t taper but should. This was a mistake in not understanding this area. The mast is slightly tapered from the base to just above deck level ie. 24” before tapering again before reaching its maximum diameter of 3-1/2” for a hollow birdsmouth spar. In answer to your question the hole should match the mast taper.
c) The plan view on Sheet 2 appears to depict the smallest diameter of the mast at the top and the widest diameter of the spar overall. In other words a plan view with the mast in place. This outer circle you refer to could be either 3” or 3-1/2” depending upon the type of mast construction. Mine is 3-1/2” being consistent with the hollow spar plan on Sheet 9. It’s weird because you are the second person taking great heed of the data on Sheet 2 when Sheet 9 provides all the facts about the spars. The only data I see there is the positioning of the spar not its dimensions. Mind you I have not purchased the plans, I’m building out of the book plans.
Meanwhile, work continues with the Mast Supports – the Bow Support is complete except needs finishing and the piece of matting installed. The Stern Support is coming along and will sit inside the Coaming and fit into a slot in the center seat board. Also the mast cutouts in the top of the Supports need lining with some spar friendly material. It’s a toss-up between some leather or more of the matting.
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So... just the top of the Aft Mast Support to be added, the Tenon and the bottom Seat Plate installed and we're ready for finishing.
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162 Mast Support Trailering Cont 2…
Hi Greg, thanks for the comments - not sure I understand the 6' remark! All the rigging can be completed prior to install each time. Can't be that hard!
All fitting is now complete on the Supports and ready for finishing with the exception of the fixings required to marry the Rear Support to the Coaming piece. I attached a brass plate to the seat to ensure the bottom of the Support doesn’t wear a hole in it.
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Unfortunately my existing Mast Collar fitted to the Deck does not meet my needs in that it is made from a single piece of wood and considering some previous comments I have decided to create a new one with grain orientation in all opposite directions. I have added a 3mm piece of ply between the top and bottom opposing pieces. The idea is strengthen this area.
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163 Mast Support Trailering Cont 3…
Finishing has commenced to the stage where three coats of epoxy have gone on the two uprights and my new Mast Collar - all sanding complete.
Unfortunately I now have to wait for more undercoat to be delivered! Ah well, the update is better than nothing!
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163 Mast Support Trailering Cont 3…
Moving on with the painting of the Supports and now have 5 coats Primer, 2 coats Pre-Kote and two coats Brightside. Used old paint colour from a previous build and got into trouble with the better half as the cream doesn’t match the boat! My view of the world is the Supports don’t belong to the sailing configuration and it was free so don’t see the issue! :innocent:
After fitting I realized that the Rear Support needs a wood tapered piece with a thin piece of foam inserted where it meets the Coaming so am in the middle of getting that ready - not finished yet, hence the tape.
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Also finally attached the deck mounted Mast Collar so now that needs finishing – undercoat and finish coat. All time consuming.
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I have also made a move on the Mast and begun the slicing up of the roof rafter I have (Oregon pine). Looks OK but definitely in need of a bit more wood – too many nail holes on one side so it appears I will only get 6 of the 8 staves required - disappointing, I thought I had it covered. :C Before I commit though I need to do more sawing to see what I finally get. :?