Thread: GIS Yawl

Yes, that note is on there. I did it for my Goat and MSD patterns but for another skiff I do I just counted it as extra freeboard. It always happens that frames and stems, etc. were cut flush to the top of the plywood, but when the rails were added, the top of them was higher than the flush cut pieces. With GIS and MSD, the sheer is the top of the rail with the rabbet. WHen I cut the side panels I just deducted 3/8". So the stem stays the same.

I also rabbet the dagger board cleats over the top of the plywood there. I do it whenever it is easy to do and cover up end grain. If it is not easy I don't do it.

In the GIS the frames tuck inbetween the inwale and plywood, where the spacer block goes.
So how does a GIS bulkhead frame intersect the closed inwale without the spacer block?
Does it save any weight?

I drew a closed gunwale based on the MSD skiff. For the Goat, you need open gunwales, with spacer blocks. So the blocks go on after the rail is fastened and the glue cures, trim the rabbet flush to the panel, then glue on spacers then glue on inwale.

For the Eureka plans I did suggest that the blocks be glued to the inwale. This is also a legitimate method.

I've done both ways, glue blocks to inwale first or glue blocks to boat first. What I do like about glueing to inwale, first, is that you can prefinish the inside of the inwale with the spacers glued on. I've actually fully painted the inside of inwales and then glues them on with only needed to add another coat or two in the tight space inbetween. Open wales are a pain to maintain, so the more finishing early on the more coats the better.

The sketch I drew up is NOT Goat Island Skiff specific, just conceptual so it can be applied to other boats. It is another way to do it, not necessarily THE way.

The other thing I am working on is locating the position of the mizzen athwartships. It is interesting the variation I have seen and used. In some boats the mizzen is Wayyyyyyy to the side so the tiller needs to be all the way over hard to come close. In the attached you can see a mizzen placed very close to the centerline. I think this is the best for the Goat, a boat that we roll tack anyway (partly) and don't need to push the tiller hard to lee, and if we did do that we'd only stall the boat. A foot or so off centerline would be fine. I'm going to mock it up and see.

Originally Posted by Compass Project

The other thing I am working on is locating the position of the mizzen athwartships. It is interesting the variation I have seen and used. In some boats the mizzen is Wayyyyyyy to the side so the tiller needs to be all the way over hard to come close. In the attached you can see a mizzen placed very close to the centerline. I think this is the best for the Goat, a boat that we roll tack anyway (partly) and don't need to push the tiller hard to lee, and if we did do that we'd only stall the boat. A foot or so off centerline would be fine. I'm going to mock it up and see.

With a small boat as light as the Goat I wouldn't offset the mizzen at all. Place the mizzen dead centre and just have a curved tiller. Bigger, heavier boats OK, but not the GIS.

I think the curved tiller will be problematic because the mizzen is far aft, only 3" fwd. of the transom at tank top level. It can be offset and not much so, and the tiller will hit if you are hard-a-lee but only if the tiller is too far over. Another rationale would be that pushing the tiller over past like 25 degrees is only stalling the boat. I don't know what the degrees are, I just know from experience that in a light boat, we want the rudder over only enough to start the boat turning and our weight (roll tack type of weight shift) does the rest. Besides, if you end up in irons, back the mizzen and you can complete the tack.

Originally Posted by Compass Project

I think the curved tiller will be problematic because the mizzen is far aft, only 3" fwd. of the transom at tank top level. It can be offset and not much so, and the tiller will hit if you are hard-a-lee but only if the tiller is too far over. Another rationale would be that pushing the tiller over past like 25 degrees is only stalling the boat. I don't know what the degrees are, I just know from experience that in a light boat, we want the rudder over only enough to start the boat turning and our weight (roll tack type of weight shift) does the rest. Besides, if you end up in irons, back the mizzen and you can complete the tack.

I've just realised too that the curved tiller is also out of the question because it comes through the transom and the bow would hit the transom. Another possibility is to have a tiller stick on the front of the back seat connected by a simple pulley system to the stock?

...Like in Beth. Yes, we could do that....but I may stick with the offset mizzen and existing tiller to keep things as original as possible. Here is another picture of an offset mast. The offset isn't much in these boats! Or maybe it looks that way...

The essential question is: How much mizzen offset is enough to give the tiller enough clearance to swing such that the helmsman has enough steerage to get the boat through the wind?

In the images of John's model mock-up, he went with the assumption that we want a 45-degree swing, represented by his triangle. One image shows how the mizzen, halfway between centerline and the edge of the tank top, will give almost 45-degrees of clearance. One image also shows the new mizzen location to give full 45.

What I do know is that the mizzen is about 3" from the fwd face of the transom, to give an idea.

I'l have an answer soon after a mock up. I appreciate ideas in the meantime.

Originally Posted by Boatmik

For the Eureka plans I did suggest that the blocks be glued to the inwale. This is also a legitimate method.

I built a mockup of Clint's idea. The thickness of the wood that has the rabbit is a little too thin because of a bad cut on my part. Everything else is dimension per Mik's plans. Ignore the cedar plank that is pretending to be the 6mm plywood. It's an old piece of fence. I just could not cut a chunk of marine plywood just for the mockup.
After building this, I think I will glue the spaces on the inwale after a careful dry fit and marking. Then apply the finish before bending it on.

Originally Posted by john goodman

I built a mockup of Clint's idea. The thickness of the wood that has the rabbit is a little too thin because of a bad cut on my part. Everything else is dimension per Mik's plans. Ignore the cedar plank that is pretending to be the 6mm plywood. It's an old piece of fence. I just could not cut a chunk of marine plywood just for the mockup.
After building this, I think I will glue the spaces on the inwale after a careful dry fit and marking. Then apply the finish before bending it on.

Remember too you will need to notch the transom end, and this can be marked out during the dry fit.

Bruce, Notch what? The rail will just run past the transom and be cut flush.

Considering that this additional sail is just a little jigger I would like it to interfere with the rest of the building and planned structure as possible.

The best way is to have it close to the transom and offset the minimum amount needed to retain a straight tiller. Anything else is becoming more complicated than is warranted.

Just think of the original boat for a moment and how the simplicity appeals. That's why the boat exists in a disinct place.

Michael.