Building Shesha, a Hunter Valley GIS, Australia

[m2c1Iw]

Hi Bruce she does look great.

Re your question about the leech cord start off with it only just tensioned then depending on wind speed increase to stop any flutter. I would not expect much tension is required at all especially on a new sail too much will create a curl which you don't want.

Looking forward to the splash have fun

[woodeneye]

Thanks for the kind comments guys!

When you start out on such a project, you have hopes and probably some expectations that it will be something you can be proud of. Now, when I stand back and take it all in, and reminisce about the various steps that brought me to the end point of the project, in a way it all seems a bit surreal.

Mr Storer has a lot to be proud of too. During the build I came to appreciate how well his Goat Island Skiff concept was thought out. There were several "ahaa" moments along the way when I thought "you cunning so-and-so boat designer".... Sure, there are various ways to do things, but Storer's way is generally the best way, and if you ever build one, you'll see for yourself. The plans are quite easy to follow and interpret and the support on this forum is amazing, so thanks to all who have helped me along the way. Some of you became quite frequent email and message correspondents and I'll be thinking of you all when the big splash happens, hopefully this Sunday if the weather is kind.

Actually, it won't be a big splash at all. Whitewood (John), your Paulownia has contributed to a huge weight saving. In the sailing world, weight saving = performance, so I have a lot to be happy about in choosing Paulownia for the framing and some other elements as well, which I'll document in detail soon so that others can benefit from this amazing timber. The hull, fully coated inside and out with 3 coats of epoxy and 3 coats of marine varnish, but without fittings, finished up under 50kg. 49.5kg to be exact. I believe that is 109lb in the language of our American friends. That's not bad at all for a boat 15'6" and a beam of close to 5'.

Designers talk about boats in terms of pounds per foot of length (or the metric equivalent) when comparing different boats and to get an idea of performance potential. Some of the more highly evolved wooden racing boat designs achieve 10 lbs per foot. Michael's GIS easily achieves 8 without much trouble using just standard timber types. Mine comes in at 7, so it just goes to show what is achievable through timber choice alone. Sure, I did also use Andrew Denman's Joubert marine ply (Gaboon/Okoume) which was consistently light across all 6 of the sheets used, but otherwise I did not make any conscious decisions to cut weight by making any significant changes. The small changes I did make, actually added weight.

So if weight saving = performance gain, then to use the words of my brother today, "your Goat's gonna do more knots than your undies can cope with"

[john goodman]

Thanks for the kind comments guys!

The hull, fully coated inside and out with 3 coats of epoxy and 3 coats of marine varnish, but without fittings, finished up under 50kg. 49.5kg to be exact. I believe that is 109lb in the language of our American friends. That's not bad at all for a boat 15'6" and a beam of close to 5'.
So if weight saving = performance gain, then to use the words of my brother today, "your Goat's gonna do more knots than your undies can cope with"

WOW! Great job on keeping the weight down.
My Goat came in at 140.8 pounds (64 kilos). 14 kilos difference, that is amazing. I had no idea there was a tree out there called a Paulownia. I changed a lot of details including adding the mizzen, but the weight I added for the mizzen and forward mast step does not account for all that 14 kilos. You wood selection was perfect for a light boat. Good job

[Boatmik]

Thanks for the reminder Mick. I should have done it today, but I was like a kid with a new toy, so it slipped my mind. I'll make sure that I do that during the week.

I put the yard attachment point at exactly 40% from the front. It seems to look right to me at this spot. What do you think?

It does look fine. Maybe both the yard and boom can move a bit forward. The angle of the boom looks OK, perhaps a fraction too high at the back - but it might be just right too.

I noticed that when I slacken off the downhaul in the light breeze we had today on my driveway, that the boom moves forward. In conditions when I don't need so much downhaul, do I slide the downhaul attachment forward to keep the boom in roughly the same spot? Or does it mean that I need to move the attachment point on yard further back, ie. toward the middle to help balance things?

You won't ever have the downhaul that slack when sailing. It does drift a tiny bit further forward in some conditions but it wouldn't be more than 25mm.

Also, I was surprised to see the mast bend as much as it did when applying lots of downhaul and mainsheet. I was not expecting this as I had assumed that because the sail was only attached to the top of the mast that mast bend would not be too great. The rig appears to be very flexible all round. Is the mast bend that I'm seeing normal?

There should be some mast bend but it should not be all that great, but to see 25 or 35mm would not be unusual. The mast is standard?

MIK

[woodeneye]

Hi Mick

OK, I'll try sliding the ring attachment further up the yard. I guess the sweet spot really comes down to the setting that gives the right amount of weather helm? Currently the luff is about 380mm in front of the mast.

35mm is about the amount of bend I'm seeing in the mast. The mast is to spec size wise, except the hoop pine used was dressed to 10mm, even though it was classed as 12mm. I weigh 72kg and the mast takes my full weight easily when suspended by the tips, so I'm pretty sure it has plenty of strength.

The hollow boom seems fine too. It's pretty stiff. It is just el cheapo radiata pine with Paulownia infills at roughly the same spacing as your inwale spacers. It's probably over engineered, but then using Paulownia there's not much of a weight concern.

I had a day off work so this morning I practiced reefing. I've never reefed a sail before so I thought I'd better see what was involved. It was a good job that I did, otherwise I would never have realised that you need double the length of rope for the new clew and tack as these have to be in tension by tying them to the ends of the boom, just as you do normally.

Also John, here is the pic you requested showing the attachment of the sail to the front of the yard. By the way, cable tie has been replaced by a lashing.

I realised I haven't yet posted a pic of the rudder stock. The pin for the rudder stock isn't fully inserted as it is a really tight fit due to the new nylon bushings in the fittings and I needed to remove it after the pic was taken. I still have to drill the holes for the rope handles on the foils. Another job I nearly forgot!

Attachment 138934 Attachment 138935

Attachment 138936 Attachment 138937

Attachment 138938

[Boatmik]

Fantastic that you tried the reefing. It is a good thing to see before you need it.

[IanHowick]

WOW! Great job on keeping the weight down.
My Goat came in at 140.8 pounds (64 kilos). 14 kilos difference, that is amazing. I had no idea there was a tree out there called a Paulownia. I changed a lot of details including adding the mizzen, but the weight I added for the mizzen and forward mast step does not account for all that 14 kilos. You wood selection was perfect for a light boat. Good job

Congratulations Woodeneye on the light weight record! Are you and John Goodman comparing like with like - bare hull without rig,foils or rudder box, what's the standard. The weight difference is a lot - more than 20%, and if I'm reading correctly you both used Joubert Gaboon ply throughout so the weight difference is all in the framing.

What framing timber is in John G's boat? I see a little extra structure in his boat - front of the middle seat and extra mast partners, but even taking that into account, it's a big weight difference.

Woodeneye, you used Paulownia for all the framing (as I am doing, but so did Peter Hyndman with plan set #1, and his came out at 57kg from memory). I'm curious as to your secret!
What's in your gunwales/ inwales and spacers?

Ian

[john goodman]

Congratulations Woodeneye on the light weight record! Are you and John Goodman comparing like with like - bare hull without rig,foils or rudder box, what's the standard. The weight difference is a lot - more than 20%, and if I'm reading correctly you both used Joubert Gaboon ply throughout so the weight difference is all in the framing.

What framing timber is in John G's boat? I see a little extra structure in his boat - front of the middle seat and extra mast partners, but even taking that into account, it's a big weight difference.

Woodeneye, you used Paulownia for all the framing (as I am doing, but so did Peter Hyndman with plan set #1, and his came out at 57kg from memory). I'm curious as to your secret!
What's in your gunwales/ inwales and spacers?

Ian

I weighed the GIS yawl in the same stage of construction as below. No rig, hardware or foils. Weighed mine on the bathroom scale at the boat balance point.

"The hull, fully coated inside and out with 3 coats of epoxy and 3 coats of marine varnish, but without fittings, finished up under 50kg. 49.5kg to be exact. I believe that is 109lb in the language of our American friends"

I used Western Red Cedar for framing and spacers. It's density changed depending what color it was. I think it had to do with how close the board was cut from the heart wood. The darker color was just a little heavier(inwale spacers).

The rabbited gunnels are spruce. and that is where the highest weight gain happened when comparing the boats as standard Goats. The additional middle seat depth and false forward bulkhead added a few pounds.

My inwale and rub rail are fir, which I consider a heavy boat material. I will try to collect some weighs from the standard sizes of my materials based on the instructions.

[woodeneye]

I weighed the bare hull without fittings or foils etc. John's GIS should weigh more as he has more structure under the rear seat for the mizzen mast and he has enclosed the mid seat. Sure, it would not account for 16kg, but the thing to realise is that the Goat isn't small. So if as he says some of his WRC was cut from close to the hardwood and was quite dense, then that would add up quite quickly over the entire structure.

From my experience of it, Paulownia is remarkably uniform and doesn't seem to exhibit much variation in density like most timbers usually do.

For the record, these are the timbers I used:

• Ply - Joubert Marine ply 6mm
• Framing - Paulownia
• Stem - Paulownia
• Inwales - Hoop pine
• Inwale spacers - Paulownia
• Transom stiffener - Hoop pine
• Bow piece - Hoop pine
• Mast step and partner - Hoop pine
• Inner gunwale - Hoop pine
• Outer gunwale (rub rail) - Meranti
• Bottom skids - Meranti capped with 2mm x 20mm aluminium strips
• Dagger board case structure elements - Paulownia
• Knees - Hoop pine
• Chine logs - Paulownia

I varied from the plan by adding more support structure (19 x 19mm Paulownia) under the front and rear seats. I also made my mid seat wider by about 50mm.

Coatings were 3 coats of epoxy (West 105 + 207 hardener) followed by 3 coats of marine varnish. Varnish is a lighter solution than paint. (White is the heaviest paint due to the pigment density, and blue is the lightest)

Glue was West 105 + 205/206 hardeners.

Anti-slip is caster sugar.

Fixings, ie. screws were all removed, except for 2 x 1.5" SS screws which are the only screws remaining, and that was unintentional.

Glass: I have not glassed any parts of the hull. The decision not to glass the chines was taken as I took pains to get a good fit of the bottom at the chinelogs. None of my ply boats have had glass, and none of them leaked or sustained anything but minor damage which was easily repaired. I would glass the chines of a S&G hull though, or if it would be used on a pebbled beach for example.

Is it possible to go lighter? I think so, but not by much. The hoop pine I used was reasonably dense, and a lighter timber could be found. Also, I think it would be possible to use Paulownia more extensively. For instance, the inwales and gunwales are timbers that run the whole length of the boat, so using Paulownia for these elements would likely have saved me another 2-3kg. I went with Hoop pine here for aesthetic reasons. Mick might comment on whether this would be stretching it a bit, but I don't feel that would be the case at all.

Until I coated with epoxy, I was a little worried that the Paulownia would be subject to denting and knocks. However, it's amazing how much toughness epoxy imparts to a softer wood like Paulownia, so I'm no longer concerned about that.

Durability. Paulownia has similar properties to WRC, except that Paulownia resists splitting better. Paulownia resists warping, splitting, shrinkage, insect attack and rot, so a Paulownia boat should be as durable, if not more so than most other plywood boats, provided it has the proper care.

[Boatmik]

Howdy,

Peter's Gruff, which might be for sale soon, was built with Western Red Cedar. Paulownia hadn't happened at that stage.

But the cedar and oregon at that time was still around in bulk so you could choose nice stuff.

There will always be significant variations in timber weights - so the biggest variable will be there. However glass adds quite a lot too.

MIK

[woodeneye]

Howdy,

Peter's Gruff, which might be for sale soon......
MIK

You know you just have to have it Mick!

[IanHowick]

Is it possible to go lighter? I think so, but not by much. The hoop pine I used was reasonably dense, and a lighter timber could be found. Also, I think it would be possible to use Paulownia more extensively. For instance, the inwales and gunwales are timbers that run the whole length of the boat, so using Paulownia for these elements would likely have saved me another 2-3kg. I went with Hoop pine here for aesthetic reasons. Mick might comment on whether this would be stretching it a bit, but I don't feel that would be the case at all.

Until I coated with epoxy, I was a little worried that the Paulownia would be subject to denting and knocks. However, it's amazing how much toughness epoxy imparts to a softer wood like Paulownia, so I'm no longer concerned about that.

Thanks for the detailed information, John Goodman and Woodeneye, interesting to see how much difference timber selection makes. I'm doing all the framing in paulownia, mine seems to be a consistent density of 275kg/m^3 from a few pieces I measured/weighed. I've also been thinking along similar lines to your comments above, maybe I'll continue on my build thread:

https://www.woodworkforums.com/f169/g...52/index2.html

Ian

[Joost]

Peter's Gruff, which might be for sale soon, ...

Peter cannot sell it! Quoting from his website about the GIS (which website really convinced me that the GIS was the boat I had to build):

"The kids have grown up and married and have begun producing kids of their own, but they still won't let me sell it, they see it as an heirloom. I'm glad I won't be round to see them fight over it!"

[CCBB]

The rabbited gunnels are spruce. and that is where the highest weight gain happened when comparing the boats as standard Goats. The additional middle seat depth and false forward bulkhead added a few pounds.

My inwale and rub rail are fir, which I consider a heavy boat material. I will try to collect some weighs from the standard sizes of my materials based on the instructions.

Rabbeted Spruce is not adding weight but saving it...depends on the SPruce used I guess. Our spruce, like Sitka, is about the lightest to strnegth ration you can get for about 1/4 the cost of Sitka. DF is a bit heavy for a boat like the GIS, but you can't beat the strength you gain.

[Boatmik]

Yes, on average the spruce will be lighter than oregon/fir. The only reason I didn't suggest the spruce is that it is super expensive in some countries and unavailable in many.

MIK