Another UK GIS (Gizzle in Hants)

[Gizzle]

Hi all,
Having just bought the plans I have been having a good read through before purchasing the materials to start the build. I'll be sure to post some pics of the build once underway.

One thought I had was around sail material, I imagine that all Goats have been build with dacron/polyester sails and I wondered if there was much to be gained from using a more modern laminate sail material.

I would think that a Dacron sail will be more tolerant of abuse but is also going to stretch more than a laminate where you get more stability of shape. Perhaps there is little to be gained on a sail of this size.

Any thoughts on this....?

(for the discussion of cloths for home sailmaking we moved it to a separate thread here
https://www.woodworkforums.com/f169/a...9/#post1246265 )

George

[davlafont]

Greetings George,

I'm no authority on sailing, sail making, or anything really. But I have worked with the US defense industry for the last decade and your question reminds me of one I've heard often before. When is good enough REALLY good enough? Or put another way, when is better not really any better at all?

I'm also not an engineer, but a systems engineering approach might be to determine if the Goat is being "held back" by the use of Dacron. We all know a chain is only as strong as its weakest link. If the Goat's weakest link is not the sail material, there's a good chance that using a high tech fabric will only expose the weak link faster or more frequently or both.

That said, half the beauty of the design and the process is how nicely it lends itself to experimentation. I have read numerous threads where M. Storer has cautioned that he will rarely discourage deviation, but will usually ask "why?" Sometimes the answer is, "because I feel like it!" and I think that usually wins the day.

I've had to defend work I've done to my car in those terms to my driving buddy/mechanical engineer. "Why install an oil cooler? Do you suffer from overheated oil? Is it costing you time on the track?" "No, I just want one because I can and they're cool, so shut up math geek."

So I look forward to following your build and can't wait to see the cool laminate Lug (radial cut I hope) that drives her!

[keyhavenpotter]

Hi George, great to hear there will be another Goat in the UK. Where about's are you - I am south coast based.

A laminate lug sail would be a lot of fun to try, if you can obtain the laminate at reasonable cost. I would use Sailcut4 to design a broadseamed sail, then glue the panels together, using 3M 5200. It would be great to be able to see where you are going and that no one is going to starboard tack you when racing.

Our local Hood loft tried making laminate lug sails for our local Scows. They were cut quite flat so lacked power compared to the Sanders sails. The other thing people mentioned that the stiffer cloth was much harder to "read" when sailing. The luff no resonding to lift the same as a soft dacron sail.

When I have used laminate dinghy sails, they do set superbly but they are horrible when dropped into the boat. Just completely fill the hull. where as a dacron sail bundles up easily.

I found that finding suppliers who would deal with you was the hardest issue. They all deal company to company and not individuals. After searching for months and getting all the bits by driving miles, I found an e-bay supplier who sells cover materials on his site but does supply all you need of the proper items.

That's the correct sewing thread, correct sailmakers double sided tape, star grommets and the closing tools. he can also supply any sailcloth you need.

Good luck with it if you do make your own sail.

Let me know if you would like contact details with my ebay supplier.

Brian

[Boatmik]

This discussion about sailcloth became so useful we organised to keep it as a separate thread.

You can see where the discussion went to here
https://www.woodworkforums.com/f169/s...-sails-127918/

MIK

[Gizzle]

Thanks for responding gents,
on another line of thought, this is probably a question for Mik but other builders may also have views....

I'm going to be buying the materials shortly and I am keen to keep the weight of the boat as low as possible so will be using Okoume Ply as suggested in the materials list. However rather than using 6mm everywhere is there any scope to use thinner ply on any of the major hull components? Wondering if I could I get away with 4 or 5mm ply anywhere?

Are there any tip's for keeping weight out of the hull in the build process?
Cheers

G

[woodeneye]

Hi Gizzle

Welcome, the Goat is a great choice.

The best weight saving tip I can give is build to the plans. Apart from extra structure that are determined by your specific needs like yawl rigs and mid seat boxed tanks, the boat is well engineered as is. The main thing affecting weight is material choice and by selecting Okoume marine ply, that is a good start because this is the main timber used. The Goat is quite a large dinghy so using heavier or larger sized timbers than specified will quickly add up.

If you can, choose timbers from the lighter end of the spectrum. Western Red Cedar is great if you can get it, but there are substitutes like the Chinese native Paulownia that work well. I used it for framing, chinelogs, stem, gunwale spacers, cb case and rudder spacers, mast/boom infills. I've driven my boat pretty hard without problems.

There is a GIS in New Zealand that will likely turn out to be the lightest yet. Some weight saving techniques are being used in that build so check out Ian Howick's thread: https://www.woodworkforums.com/f169/g...ealand-115452/ Ian has some useful building techniques too.

[john goodman]

Hi Gizzle

Welcome, the Goat is a great choice.

The best weight saving tip I can give is build to the plans. Apart from extra structure that are determined by your specific needs, the boat is well engineered as is. The main thing affecting weight is material choice and by selecting Okoume marine ply, that is a good start because this is the main timber used. The Goat is quite a large dinghy so using heavier or larger sized timbers than specified will quickly add up.

My GIS hull weighed in at 142lbs, with its extra mast steps for the yawl rig. I think I would have been in the 130lbs range without the yawl/mizzen mast steps. My Douglas fir breast plate and knees are thicker than the plans call for because we wanted the "look" of strength. Added some Douglas fir trim around the daggerboard slot and made the middle seat a little wider. With each of these little adds/changes my GIS got a little bit heavier. So be careful with what you add. When cutting your timbers don’t think an extra mm will be adding strength, because it really only adds weight.

It's all those little ounces that add up to the extra pounds.

[Gizzle]

Hi Gizzle

Welcome, the Goat is a great choice.

The best weight saving tip I can give is build to the plans. Apart from extra structure that are determined by your specific needs like yawl rigs and mid seat boxed tanks, the boat is well engineered as is. The main thing affecting weight is material choice and by selecting Okoume marine ply, that is a good start because this is the main timber used. The Goat is quite a large dinghy so using heavier or larger sized timbers than specified will quickly add up.

If you can, choose timbers from the lighter end of the spectrum. Western Red Cedar is great if you can get it, but there are substitutes like the Chinese native Paulownia that work well. I used it for framing, chinelogs, stem, gunwale spacers, cb case and rudder spacers, mast/boom infills. I've driven my boat pretty hard without problems.

There is a GIS in New Zealand that will likely turn out to be the lightest yet. Some weight saving techniques are being used in that build so check out Ian Howick's thread: https://www.woodworkforums.com/f169/g...ealand-115452/ Ian has some useful building techniques too.

Thanks Woodeneye,
Planning to use Ocoume Ply, WRC and Douglas Fur. Probably something harder and heavier for the hull runners (Oak or Iroko).

Will take a look at your link for tips.

Cheers , G

[Gizzle]

My Douglas fir breast plate and knees are thicker than the plans call for because we wanted the "look" of strength.

Nice Knees and a neat job, hope my GIS is as good.

[woodeneye]

Thanks Woodeneye,
Planning to use Ocoume Ply, WRC and Douglas Fur. Probably something harder and heavier for the hull runners (Oak or Iroko).

Will take a look at your link for tips.

Cheers , G

Good choices, you'll have a light boat.

As you will see from Ian's techniques, he is capping lighter, softer woods with a hard wood where required. You could do this for the runners, ie. use a lighter wood and cap with a sacrificial piece. I used aluminium to cap my runners, but the cheaper and lighter way is to cap with a hard wood.

Check out his transom stiffener. There is extra ply available from the sheets to do this sort of thing, so it's a great way to go.

[IanHowick]

Sorry too busy now, but I'll try and document a list of my weight saving ideas by tomorrow.

One thing though - if you are dedicated to light weight, if there is any way you can get Paulownia timber, go with it, 20% lighter than Western Red Cedar with similar strength but less likely to split. I can get it more easily down here than WRC, but that may not be the case in the UK.

Ian

[blanche]

Put mcnamara sails into google,he made my sail and its brilliant,he's located in Norfolk.
Blanche.

[keyhavenpotter]

Hi Blanche, I read some where that your Goat had very little epoxy used in the build, or was it none at all? Was it resorcinol glue and standard paint undercoats and topcoats, plus spar varnish? All that 3 coats of epoxy is unpleasant and expensive to do.

Brian

[blanche]

Blanche was built using Aerolite 306 glue and finished with marine paint.

[Boatmik]

Hi Blanche,

Are you Richard or Mark?

The McNamara sails have been very well regarded on this forum. Particularly that he sailed the boat and then wanted to get the sail really right. Very impressive. And he is not as expensive as some.

Best wishes
Michael