Annie wrote:

To be honest, my own opinion is that if the wood structure is strong enough, all it needs over it is some light glass cloth to provide a hard and thick surface of epoxy.  However, David told me to put bi-axial cloth on the skegs (and rudders and bilgeboards) and Pete said to put it on the tabernacle.  They are the experts, so I did as I was told, but I don't understand how or why this fibreglass adds any real strength to such large pieces of wood.  I don't like using bi-axial cloth because I find it difficult completely to wet out, without there being at least some bubbles left in the matrix.

I hope that someone with more technical expertise will chip in and enlighten us both!

Which David said that? Fanshi's skegs and rudders would be mega stiff, without any sheathing. I will certainly have advocated thick glass sheathing on underwater surfaces, to provide maximum impact protection against the possibility of bouncing the hull and control surfaces on sharp rocks etc. Biaxial glass is quite thick, and would build up the laminate quickly and smoothly, but its fibre orientation properties are not required. Woven rovings would be just as good. (But having said that, it's much easier to persuade glass cloth to conform to sharp bends such as the leading edge of a skeg, if the fibres are at +/- 45˚).

I would put unidirectional glass on the bilgeboards, vertically oriented, as they are designed to be relatively lightly constructed for ease of operation, and more stiffness will be a good thing. For tabernacles, I would have thought that heavy glass would be for peace of mind as much as any technical reason. For thick decks, I would put on more than a thin glass sheath, but only to protect against dropped tools and the like. For thin decks, that thicker layer of glass becomes structural as well.

I have seen a demonstration of how 6mm plywood is made twice as strong by coating it with epoxy on both sides (at Hobart Wooden Boat Festival). Thin glass would have added more strength, but I haven't seen that demonstrated. It's a question of the relative thickness of the glass and the wood, I think. A thick piece of strong wood , as in a tabernacle, would not be further strengthened by adding epoxy and thin glass, but a thin hull of cedar strip planks absolutely depends on layers of glass on both sides, for both point impact resistance, and also overall stiffness and strength.

In case anyone is interested -- I am trying to keep my rig conversion moving along. There was some unusually cold weather here last week and I was not able to do any epoxy work. The photo attached is from two weeks ago when the temperature, according to my cooking thermometer, was just above 40 Deg F. Epoxy seemed to cure without any issues overnight using the West System fast hardener.

Yesterday I went out in the snow and did some sanding and grinding with the angle grinder. I think I now have the closest thing to a 'good fit' between the sides and center that my skills will allow.

I am trying to follow the JRA article and the work documented on Voyaging with Annie Hill.

Does anyone have a suggestion on when I should use fiberglass? I was planning to just use thickened epoxy to join the sides to the center section. Then I noticed that Annie put glass on the top of the side sections and also on the lower part of the middle section. It appears she let it cure before doing the final assembly.

I do not completely understand how fiberglass and wood composites work to make stronger materials. I suspect that there should be almost zero gap between the wood pieces for it to be effective. Should I use both glass and thickened epoxy? I wonder if that will make a weaker joint compared to glass alone.

I am seeing some highs up above 40 in the forecast this week. I hope to keep everything inside and warm (~66 Deg F) and then move it outside to mix the epoxy, clamp it and screw it together.

Just to be clear -- the photo showing professional quality wood work done in a proper boat shed is from Annie's blog. The photo with misaligned pieces featuring a cooler in the background is mine. I hope it is OK I borrowed your photo here, Annie. Please let me know if you want me to take it down.

Thanks for the replies. I plan to use tapered pole. The boat came with a gin pole setup that makes it relatively easy to raise the original mast. I hope to re-purpose it for raising the freestanding mast.

I decided that I would somehow find a 7" pole and then started building a Tabernacle. I learned the hard way that west system slow hardener must be used at 60 deg F or higher. I thought 50 deg F was the minimum. I was wrong!

I used 2x dimensional lumber which is actually 1.5 inches thick. The article in JRA magazine issue 61 article recommends 2" lumber. I hope 1.5" actual is close enough for my small boat. If anyone thinks this is too lightly built please let me know.

I am stuck now because I can't think of a way to make the sides of the tablernacle bend for the taper. Do I need to buy something like 10 big clamps to make it bend? I attached a photo.

Any advice is appreciated as always!

Hi Scott,

my suggestion would be not to compromise on the strength. This eliminates the first and last option. The wall thickness is not too important, this requirement is more related to the ease of damaging the section and as long as it is more than about 3.5 mm thick then this should not be a problem. I would go with the third item on the list as the weight is closer to your aim than the second.

All the best with the project.

David.

Thanks to everyone who took the time to give advice on the mast.

I now have 6 layers of 1/2" fir plywood glued into the hull. I also have 4 more layers laminated together for the top of the mast step.

I am sure I would do it better on the second try ... But I guess I have to learn somehow. I am not terribly proud of the crooked base and I only really got the top two layers glued in the way I would like them all to be. I should have used much more epoxy, I think.

On the other hand if needed to remove it I have no idea how I could get it out without first chipping all the wood into little pieces and then grinding the epoxy off the hull. Thinking about how difficult it would be to remove intentionally gives me some confidence that it is strong enough.

I am pretty happy with how the top section turned out.

It seems that considering epoxy a recurring expense like boat storage makes more sense than thinking of it as a one time expense like buying a boat.