[renahoyle93048]

Hi Waynet,

Welcome to the Sabre family.

I endorse Harold’s comments about a strong back. I would further add that if you use a strong-back you make the spacer at the thwart the length that matches the finished hull because if you use the longer length recommended in the construction notes you will change the rock as you pull the sides in to get the beam correct.

I am about to start my 4th boat and will be using an aluminium batten to get the curve in the strong back and the bottom of the side panels fair. A fair boat will be faster than one with ripples from an unfair chine or keel line.

Put some of the yellow packaging tape on the top of your strong-back so if any resin goes through the joint the boat will not be stuck to the strong-back.

Regarding the glass I have used a short hair roller and a foam roller with little difference in the result. I live on the QLD Sunshine Coast so have little trouble with resin temperature.

The class rules and measurement notes call for panels 1 and 1A to be 5mm thick ply or 4.5mm thick glass / ply composite. My test and the literature published outside this forum indicates that this needs a layer of 200gms either side of the ply to comply. Please feel free to conduct your own tests.

I find that using the roller and working from the wet to the dry areas that my resin to cloth ration is around 1 resin to 1 cloth by weight and I end up with the finished laminate being between 0.1 to 0.11mm per 100gns of cloth. I have achieved these results with 100gms, 200gms, 300gms unidirectional cloth and 900gms unidirectional cloth. From a weight perspective This equates to about 200gms for every 100gms of cloth used. My experience is that 200gms cloth plus resin adds 4kg. if you go for 100gms then you will reduce that to 2kg.
If you reduce the area of glass you could save additional weight. Other posts on this forum suggest that aroung 100gms glass is all that is required. I think the heavier glass will reduce the cracking at the edges of the floor battens.

if you use a balance weave cloth run the fibres at 45 degrees to the centreline of the boat as this will end up with a stiffer panels and boat than the 0/90 direction.

I use the WEST resin because I like the ability to use metered pumps and I know all my glass and glue will be compatible.

If you ask Mr Google the right questions you will find lots of sites that have video’s of how to do fibre glassing.

Have fun and enjoy the project. Read the construction notes several times before you start and read each step again before you do it and a couple of steps further ahead also. Take lots of care to keep everything clean and remove any excess glue and resin.

I am not sure about the floor batten length conditions now. I believe we can extend them further than 25mm through the Centrecase bulkhead. I am planning on making the floor battens around 3000mm long starting at the transom. This should strengthening the area forward of the Centrecase bulkhead considerably. I believe this area is critical in getting on to the plane early.

Regards JohnL.

[renahoyle93048]

Hi John NT,

The sheets I got from Denman Marine weighed in at 6.3 kg per sheet and dropped to 6.2 by the time I got to use them.

The only ply I have found under 6kg per sheet were sheets of Kokoda (I think that’s how you spell it) and only about 1 in 10 was down to 5KG.

If you are careful with your glue glass and resin you should be able to get a 41kg boat with sheets that weigh 6kg per sheet.

Regards JohnL

[renahoyle93048]

I treated my wire with a Teflon based spray before I wired up the hull and the wire pulled out very easily.

[renahoyle93048]

John,

I have been doing a lot of thinking about this topic as I am considering building a new hull later in the year.

You comment that you think the FRP boat is softer in the cockpit area and stiffer under the mast area.

Do you have any ideas why this should be?

My current thoughts relate to the hull stiffness forward of the shrouds, flexing in the centre case area, and the flex under the mast.

Perhaps you could comment on what happens when you tension the forestay?

There seems to be a lot written about the centre case bulkhead flexing, which I think is a result of the top of the centre case flexing. I calculate that there is about 60kg side load on the top of the centre case. Please comment?

I would think that the area from about the web bulkhead back would need to be very stiff to promote early planning.

The decisions I feel I need to make include width, height and length of the floor battens, how much timber to include in the top of the centre case, and wether I use stronger timber than Western Red Cedar in the gunwales.

I would like to include a brace from the top of the web bulkhead to the bottom of the bow, but this is not allowed.

John Ladewig 1940

[renahoyle93048]

Hello,

I have just found out about the proposed rule changes.

I am concerned about some of the proposals.

Item 1 Establish a single fixed Datum point. To me this proposal contains much more than a single fixed datum point, it establishes fixed points for measurement at station 3 / centrecase bulkhead. The down stream effect of the station 3 measurement for am amateur would make the location of the centrecase bulkhead 2350mm

Item 3 Chainplate position. Reading the proposed construction notes The position of the centrecase bulkhead will be fixed at 2352+- 0mm from the transom (2380 – 24 – 4). I am certain that I cannot hit that target.

Item 11 Transom pintle spacer. Why make the spacer 15mm. I suggest that perhaps 18 -19mm would be a better size as that would match offcuts from some of the other timber.

Item 42 Change FRP mould measurement procedure. Clearly there is a strong demand for amateurs to be able to build their own FRP boats. Given this we need to establish a set of rules that allow that to happen without allowing new shapes to be developed. I am not sure that the wording in the new proposal achieves this.

Thankyou for your time

JohnL

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