GIS Yawl

**Boatmik** · 18th September 2008, 10:55 PM

Howdy Brian,

Normal solid glass cannot compete with plywood.

You should have seen the 'glass guys trying to compete with the plywood racing dinghies in OZ where the hullweights for racing dinghies are around 8 to 10 lbs a foot on average (we can forget about Moths for our two countries that got down to about 3lbs/ft)

At those weights the plywood boats were stiff, strong and reasonably durable, but the glass boats would have a competitive life of about a season and a half (if they EVER were competitive) and often came out 10 or 15lbs heavier for boats in the 12 to 14ft range.

By reasonably durable ... a couple of very early boats in the Manly Junior, sabot, Heron and sabre classes have blitzed national championships though they are 30 (maybe closer to 40 years old now.

The only way to compete with timber is to go to foam cored composites. And this is where the class associations made the big mistake ... they didn't specify how thick the core could be to match timber ... so suddenly foam glass boats were stiffer than wooden ones with the result that the wooden boats did not get a really good look in with race results any more.

This happened with the Optimist a few years back where they still had a fairly crappy timber construction method but allowed all sorts of sophistication in foam/glass.

And it has just happened with the Australian Sabre ... a very popular and cheap timber dinghy where timber boats could be built quite cheaply ... maybe $3000 (same price for an excellent timber second hand one too) .. but now if you want to win the nationals you NEED a foam/glass boat .. maybe about $8000.

Sigh.

The foam boats are prone to denting if you put them down on a stone ... so people have elaborate dollies or cradles under the boat at all times.. more expense ... and you can't really use them for cruising any more .... incase you have to land on a rough beach. With a timber boat you can IF YOU ARE CAREFUL(you may scratch paint) but the foam boats always seem to accumulate a few dents.

____________________________________________________-

Now can I move to philosophy a bit ....

The next bit might be parochial ... but it isn't meant to be

One interesting point was when they started to amalgamate the Australian 14ft dinghy with the International 14.

The big argument was over hull weight.

From memory at the time
Oz boats were 130lbs OZ14
UK/Canada/US boats were around 280lbs. International 14

The International 14 guys were already experimenting with foam and a lot of carbon ... but carbon was banned in OZ because of the cost.

THE HEAVIER BOATS WERE ALREADY USING CARBON BUT WERE TWICE THE WEIGHT of the non carbon ones!!!!

Additionally there were big concerns from the Northern Hemisphere that if they went much lighter then the boats would become unreliable .... but the OZ boats had a track record of a decade or two with very high reliability at half the weight.

It took them a decade to sort it out. The OZ boats showing good faith my changing over to the international rig specification quite quickly .. but the hull negotiations went for a long time.

So .... why were the Northern Hemisphere sailors stuck with such heavy boats when they were already using carbon!!!!

It is because of expectation ... if all the boats you are used to are so heavy ... then it is really hard to break the mindset.

In OZ we had it too ... when Ben Lexcen came up with his plywood 18ft skiffs in 1960 at a third of the weight of the planked ones at the time and with a crew of three rather than 5 or 6 they were promptly banned and it took 10 years for those changes to become acceptable.
http://www.woodworkforums.ubeaut.com...347#post706347

So .. when I look at the swallowboats ... despite they quote Carbon or timber or whatever ...

They look incredibly heavy to me!!!!

And it seems dumb that they have to move to exotic materials to get the weight down when I can easily imagine building at much less than the carbon weight in wood ... why isn't the wooden one 360 lbs??????? instead of the same in KG.

Why isn't the carbon one a shade over 200 lbs and why isn't the glass one the weight of their carbon one.

If I can't build the whole thing under 360lbs in wood ... then I know nothing about boat design and building.

BTW .. I am sure they would do a prettier job than me ... I am tempramentally unsuited to professional boatbuilding!!!!!

So .... It comes down to a culture argument again. I am lucky to be influenced by what the NZ and OZ builders have been doing for decades .. so my starting point is really different. (actually John Claridge would know exactly what I am on about too so not just NZ and OZ ... there are people doing great stuff around the world ... but most get seduced by carbon etc without really examining the possibilities of more standard materials used more wisely).

BUT ... on the other hand .. I wonder if the Swallow's weight and stability will make it a much easier boat for an average sailor to take on a RAID ... and the performance is more about average good performance than out and out speed.

However (don't I love those sentence conjunctions!!!!) why not make it OZ light and put in bigger water tanks for ballast?

MIK

**CCBB** · 19th September 2008, 08:42 AM

Hey all. I retraced Mik's drawing and made some slight changes:
-- I raked the mizzen aft a little to equal the transom rake which should facilitate building the mast partner/step/box assemblage (always thinkin" like a boatbuilder!!! Make it easy!)
-- I drew the clew of the mizzen higher to get the CE of the mizzen up higher where it will do more work without adding much sail area
-- I rechecked my scale and it was off so fixed that and got a corrected sail area for mizzen: 14 SF.
-- I also thought a little more and came up with some questions and potential solutions but will come back with those later (you'll see in the drawing that I left the boomkin out and did not draw in the sheeting arrangement; more later...)

**Boatmik** · 19th September 2008, 10:45 AM

Howdy Clint,

Aesthetics are always the hardest part to agree on, but I have some suggestions.

For some reason this mizzen looks visually weak and doesn't seem to relate well to the mainsail geometry, surprising, because in some ways it is not much different from your drawing on the first page.

Part of it might be the extra rake which has moved the mast head further away from the main.

I would suggest bringing the mizzen back to your previous drawing on page one with the same length boom as shown here in the current drawing.

I wouldn't be worried about the mizzen and transom having different rakes. It does look better that way as it makes the mizzen relate more strongly to the mainsail visually. As a building detail it means the hole at the top (partner) is a few millimetres forward of the parallel position. At any rate the parallel position makes little practical difference because the bottom of the boat and the tank top are a different angles to the transom so the measurements will be quite different. I can use CAD to confirm the relative positions if you like.

Also the mizzen has lost some visual strength because the foot (bottom edge) of the sail has lost its relationship to the angle of the main foot. They should not be the same angle, but the mizzen foot should be tipped at a slightly steeper angle than the main. This can be easily fixed by moving the existing boom you have drawn downward.

It looks like the mast is also a bit shorter than the original from page 1. As discussed the tiny Salcombe Yawl mizzens work visually because of their height ... I would recommend adding about 300 to 400mm to the mizzen mast height.

In theory this would mean a recalculation of the centre of the sail area again ... but I wouldn't bother. it is not going to make much difference and if there is a difference it will be in the right direction (weather helm). At worst it will mean the mizzen sheet will be eased an inch more compared to one with a slightly smaller area.

By the way the step and partner arrangement for a sail of this size stepped so close to the transom can be very light indeed. Many designers don't realise just how much load the deck can take from a mast so overbuild partners terribly (I did with my original BETH ... at least for the mainmast but have become gradually more daring). Probably will need little more than a block under the deck that is deep enough to prevent the mast from bruising. BTW to prevent the mast from splitting at either the end or at the partner a couple of rounds of glass tape at both positions will prevent any probs.

Best wishes
Michael

**CCBB** · 19th September 2008, 11:44 PM

Well, based on Mik's thoughts and going back to some prior thinking -- that the mizzen should "go with" the main aesthetically -- here is a revision. I like it, what does Mik think? Lets look at it next to the previous version.

Hopefully this looks good and we can look at some questions and go to the next step, more of a construction plan.

Cheers,
Clint

**Boatmik** · 20th September 2008, 11:15 AM

Howdy Clint,

I am happy with that. Looks much better. So you can go with it if you are happy too.

If it was me drawing it up, I would go for more height and shorten the boom in proportion ... just to make a more striking looking sail like the Salcombe Yawls.

Currently it is a lovely normal proportion and you can leave it there with my 100% blessing. But if you want to stir people up with a gorgeous looking rig then more height in the mizzen (without increasing area) would be a good way of doing it.

Did you see what Nigel Irens did with the lug rig on his Romilly design?

http://www.nigelirens.com/FRAMEcruising.htm

That mainsail is so tall and striking that it transforms the appearance of the boat .. and identifies it as something very different. Without that main it would be a normal classic design, but the designer's background in seriously fast multihulls creates something wonderful.

It is not practical to do a high mainsail in the GIS, but the handkerchief mizzen we are talking with such a light mast from a windsurfer ... might be worth considering.

Big downside of such a rig is controlling the sail twist. But with the Goat mizzen it is a sprit which is very effective at limiting twist.

However I am happy with your sketch above Clint. It depends on what you want to do.

Michael

**CCBB** · 20th September 2008, 08:33 PM

Mik, Thank you kindly. I "discovered" Romilly and Roxanne when I was thumbing through and old Wooden Boat mag at lunch one day...I literally coughed up my sandwhich when I turned the page on saw a photograph of Romilly. Immediately the sail rig took over. Then the classic shape of the cabin perched on a beautiful hull took over. So, my wife and I are looking for a 22-25' dayboat for us as a family and it is hard to find something as beautiful. I could build her on commission, but to do it on my own time would be hard...the GRP ones are too expensive. But, anyway, I know what you mean.

I may try stretching the mizzen vertically a little more. Not sure I can do so without having to add battens aloft.

So, the next step is to look at things in plan view and blow up the profile view and sketch out construction ideas to work out a couple issues I foresee:

1) Moving lug fwd pushes it up and reduces the spread between step and partner about an 25-35mm. Solution? Laminate a collar around the partner on the tank top to give extra support to make up difference.

2) Is the tank top for the mizzen high enough to brace mizzen? I thought a collar or two laminated onto the tank top around the hole for mizzen (in addition to framing below for both partners) would give lots of support. The alternative solution is to raise tank top heights a little bit, but would like not to have to.

3) Would the usual sheeting arrangement still work fine with the lugsail in the forward position?

4) I've seen various sheeting angles put on a sprit-boom...does mine seem OK? Or does the boomkin need to be longer? I do like a more stubby boomkin.

It is interesting that what totally attracted me intially to the Goat is the same thing that drew me to Romilly...a beautiful sail plan! So I'll sleep on this one awhile and think of the questions in the meantime.

Cheers,
Clint

**Boatmik** · 21st September 2008, 12:04 AM

Howdy Clint, Just suggesting a bit of a tweak ... for Art's sake.

You were right in the beginning about the battens ... or the avoidance of them .... stick to your guns on that one, but just tweak a little more I think.

Best wishes
MIK

**CCBB** · 21st September 2008, 02:47 AM

http://www.woodenboat.com/forum/show...29#post1952629

This is a great post with a response by a lug-yawl aficionado.

Demonstrates why I love this rig so much.

Clint

**robhosailor** · 21st September 2008, 07:36 AM

Originally Posted by Boatmik

Did you see what Nigel Irens did with the lug rig on his Romilly design?

http://www.nigelirens.com/FRAMEcruising.htm

Did you see Bjorn Thomasson Design???
http://www.thomassondesign.com/choos...arpie_600.aspx

...a bit similar to Nigel Irens's one - isn't it?

**robhosailor** · 21st September 2008, 07:45 AM

I like yawl rig for skiffs. Yawl rig for small boats proveniency from English beach boats is. I skeched similar one for Radoslaw Werszko's 4.2m skiff:

Yes MIK, I know your opinion about it

Aloha !!!

**Boatmik** · 21st September 2008, 08:29 AM

Hi Robert ... if you wanted to push comparisons further ... here is the same boat that is similar in profile to the Irens boat.

Quite different in hullshape

But compare to a Norwalk Island sharpie 18 ...

The same off centreboard and very similar centreboard profile and even the lead.arrangement in the centreboard. I drew up the ketch rig for NIS .. it took huge effort to keep the centres of the sail areas down to the same height as the original cat rig. It is difficult to get enough stability into a little 18fter with a narrow bottom so the sail area has to be squat.

MIK

**Boatmik** · 21st September 2008, 08:38 AM

hmmm ... hijacking my own thread ... back to GISs again please!!!

**robhosailor** · 21st September 2008, 08:39 AM

Originally Posted by Boatmik

... if you wanted to push comparisons /.../

Wow! Yes Bjorn Thomasson's Sharpie 600 is a clone of both them

IMHO ...

SORRY !!! I will return to GIS

**Boatmik** · 21st September 2008, 08:45 AM

Originally Posted by Compass Project

http://www.woodenboat.com/forum/show...29#post1952629

This is a great post with a response by a lug-yawl aficionado.

Demonstrates why I love this rig so much.

Clint

Yes ... this is useful with BETH too of course.

You can use the mizzen for pretty precise reverse parking. Which can be nice when there is a screeching onshore breeze and you need to go into a confined space.

Nice to go in backwards and it is amazing how far you can direct the stern by pushing the mizzen to the left or right manually.

Much nicer that with wind behind and cracking the 15knot limit!!!

With the Standard Goat I would just drop the sail offshore then just let the boat blow in going forward. There would be enough speed for steerage way and the possibility of making hte boat go a bit faster by one of the crew standing up to increase windage.

Best wishes
MIK

**Boatmik** · 21st September 2008, 08:51 AM

Originally Posted by robhosailor

Wow! Yes Bjorn Thomasson's Sharpie 600 is a clone of both them

IMHO ...

SORRY !!! I will return to GIS

Remember though that such ideas can start with a client who tells the designer what they want. But if I had the profile of the NIS showing the bottom shape and centreboard arrangement ... comparison would be even more stunning.

MIK

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