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Racundra
06-07-2017, 04:49 AM
Hi everyone

Jumping ahead a bit and thinking about the big, exciting parts of the build... (just got partially completed spars at the moment and some wood that will hopefully resemble a centreboard and rudder at some point...)

Is there a way, using the plans, that I can work out the maximum width of plywood I'll need for the widest plank of the hull? Or is there anyone on here who has built a Guillemot and can tell me? I know I can measure "plank width" from the plans (they have full size patterns for the various stations) but how to turn that into a "projected flat" width is beyond my brain at the moment.

(The reason I'm asking is that I want, if possible, to avoid having sheets of plywood hanging about at he same time as I'm planking. I'd rather cut them in advance and then lay the shapes out from the jig. Does that make sense?)

Thanks

Noel


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Bill Wiegmann
06-07-2017, 10:25 AM
I doubt what you propose is feasible. I have planked a Tammie Norrie from a kit and built an Auk from plans. When building from plans, you have to spile each plank as you go. I am not aware of any means of projecting accurately what the plank shapes will be just from the full size mold patterns in the plans. Some planks will be relatively straight, others will be quite curved, some even S-shaped.

The kits come with rough diagrams of each plank (to help in identifying and joining the halves together), but not full-size patterns. I suppose if you could get copies of the diagrams, you might be able to estimate the curviness of full size planks and then scarf up your plywood sufficiently oversize to be confident the ultimate plank shape could be gotten out of your scarfed lengths. For the Tammie Norrie, however, there were subtle differences in the stem for the kit compared with the Oughtred plans to facilitate using the CNC planks and molds. I am not sure how you would allow for that.

webishop14
06-07-2017, 12:54 PM
You might possibly be able to do it by inputing mold offsets into some free ship-designing software, such as Delft Ship, or Hull. One that will produce develop-able hull forms. From the resulting plank drawings, you might be able to approximate the shapes you need. Maybe. I've never tried.

Peerie Maa
06-07-2017, 02:24 PM
You might possibly be able to do it by inputing mold offsets into some free ship-designing software, such as Delft Ship, or Hull. One that will produce develop-able hull forms. From the resulting plank drawings, you might be able to approximate the shapes you need. Maybe. I've never tried.

Good shout, enter the data as chines in Freeship and it will give you developed shapes.
However what you propose will waste a lot of plywood.

Howard Sharp
06-07-2017, 02:56 PM
And those computer developed shapes will only fit a perfectly executed set of molds. In my limited space I put the strongback on wheels so I can make space for cutting from large sheets of ply when I need to. As has been pointed out, even rough precuts of planks will limit your ability to make the best of the plywood sheets. My memory of the Guillemot is that there's zero room for mistakes before you have to go back for an extra sheet of ply. (I ended up recutting two planks).

John Meachen
06-07-2017, 03:43 PM
Might I suggest a different tack.Could you make plank patterns with narrow strips of thin ply or hardboard,held together with hot melt glue and well braced with diagonal strips too.You could cut the planking from said patterns-with a bit added as a fudge factor.

Racundra
06-07-2017, 03:44 PM
Thanks for that everyone.

I was thinking of getting a CAD/CNC set of planks from Jordan Boats in Somerset (UK) but was also wondering about a DIY (non-cheating) approach too. (It'd certainly be cheaper than a kit, but I'm not flush with space, so it would be probably more practical, as I could stack up cut planks more easily than full sheets of ply.)


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Racundra
06-07-2017, 04:04 PM
Might I suggest a different tack.Could you make plank patterns with narrow strips of thin ply or hardboard,held together with hot melt glue and well braced with diagonal strips too.You could cut the planking from said patterns-with a bit added as a fudge factor.



I've seen people doing that (Jegs Guillemot blog, for instance). I quite fancy it as an approach... although I wonder if I'd be still keen after a few weeks of it! When I could be slapping planks on willy-nilly that have been accurately cut to fit accurately cut moulds... (and I don't have enough space to have the boat and full 8x4 sheets of ply out at the same time... (from a kit, I'd plan on scarfing all the planks before putting the strongback together, so hopefully dealing with my space issue...)


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John Meachen
06-08-2017, 04:32 PM
I think the slapping on of CNC planks might need to be a lot more precise than the "willy-nilly" mentioned or the potential cumulative error could mean that from quite early on the planks that were expected to fit might put up a fight as you strain them into position.

Racundra
06-09-2017, 01:39 AM
I think the slapping on of CNC planks might need to be a lot more precise than the "willy-nilly" mentioned or the potential cumulative error could mean that from quite early on the planks that were expected to fit might put up a fight as you strain them into position.

Haha! I was only joking about 'slapping' anything anywhere! BY:D

Although I appreciate the headsup about incremental errors... Do you think a 'cut each plank as you go' approach would yield better results?

John Meachen
06-09-2017, 04:22 PM
Haha! I was only joking about 'slapping' anything anywhere! BY:D

Although I appreciate the headsup about incremental errors... Do you think a 'cut each plank as you go' approach would yield better results?

It would at least give you the option of correcting minor errors as you go along.

Racundra
06-11-2017, 11:17 AM
It would at least give you the option of correcting minor errors as you go along.



Hmmm... well my track record is one of "minor errors" 😔


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