What's become of Plyboats?

Way to go! Not wisdom really, just an idea that popped into my dusty old mind when I read your post! I was hoping there was a way to finesse the righting moment out of that but the CoG stays stubbornly on the centerline.

You can do the same thing from the bodyplan view, save juggling the viewpoint in Perspective, and any of the 4 views can be expanded to full screen; just in case you didn't know.

Afterthought: there is probably an ideal thread to post your method for others to see in the software forum ...

 

OK,

here are my first two questions for those with some experience witht the Carene hull design software.

1. The stem angle entry on the bottom panel design page appears grayed out...cannot be adjusted..seems to stay at 15 degrees. Always so? Not a problem for me, just curious.

2. At the bottom center of the drawing/grid page there is an entry labled StationX=___. is this for entering the number of stations that will eventually be drawn? or perhaps the interval between stations? Thanks for you input. If I have more questions I will start a new thread rather than hiding this under the PlyBoats thread.




Scott

 

That's because the stem angle is determined by how the planks meet at the stem. If you enter a width for the bow transom, you can then enter a stem angle. You will then have a pram.

Enter a location here and click on Station; you can enter more than one but they are not saved, at least in my version of Carene, so you may have to re-enter them each time you open a hull design file.

 

Thanks Terry,

Pram/Garvey or default stem...not really a problem, guess on my Banks Dory experiment I'll have to vary the transom/tombstone slope to match the bow. From what I can see, the version I have won't do double enders. Wasn't really going there anyway, mostly skiffs and dorys at the mo.

 

The stem entry angle is determined by the flare of the side panels...you will notice that as the flare increases the angle of the stem rakes more. Yes..you will have to put a lot of rake to the transom to get it to double end but it will do it up to a high amount of side flare. Try sticking 40 or 50 deg in for the transom rake with a side flare of say 60 deg and you should get a double ended boat. Like I said...you can vary the stem on multi chine boats if you use the Auto planking option and play with the stem shape numbers...+ is more rounded and - is more raked. Carene will not do a curved bow shape on a single plank nor will it allow a plumb stem with side flare...you can take care of that after importing into FreeShip.

 

When I was using Carene to design double-ended canoes I had to insert the maximum transom angle it would accept which was 70 degrees, to avoid having a transom in the design. If this angle was not enough to eliminate the transom, then I did 2 designs, one for the stem as usual and another for the canoe stern which I got as the stem of a modified hull; if the canoe was symmetrical I just copied the forward half for the stern. Mostly I was just interested in getting the plank developments.

 

I had thought of the split drawing option, or of flopping a symetrical design fpr double enders. Great input on controlling the end angles by side flair and fudging transom angle and such.

 

Seeing as virtually all the stuff I do is for plywood planking, Carene is my go to to begin any hull. I can usually have what I want roughed out in less than 20 minutes then just transfer the rough shape to Freeship for the real massaging. Sometimes what looks OK in halfbreadth is either too skinny or too fat when I look at it full beam so I pop back in and adjust then reimport. What is really funny is that Carene...which is a stickler for keeping things developable will let you put "Keel Advance" into a hull (Which is a conical projection I believe)(And it does work in real world on plywood) but when you import into Freeship it reduces it significantly and tries to tell you that there are issues with it. I usually don't give too much weight to that because I have seen what kind of twist the plywood will take in that area and you can get a pretty big chin on the front end of the bottom by sewing them book-faced and opening up the panels.

 

Free!Ship will show plank distortion with a red highlight using the developability check display mode but I find plates shown mostly in red can still be formed in ply. The plate development tool provides a value for the edge error, I have been able to form plates with up to 0.005 (0.5%) without much difficulty.

I created a Free!Ship model of Rushton's classic Wee Lassie canoe, see pic. The bottom plates show up entirely red using the developability check but I made a half-scale half-model of the bottom pair of plates and they formed nicely. Free!Ship's plate development tool shows these plates as asymmetrical although the lines have fore-aft symmetry; if this happens I cut the plate oversized in the suspect zone and trim them to fit. However, for the half-model I just made the bottom/inner edges straight; the model had a lot of rocker. This confirmed that the general shape shown by Free!Ship, which was concave and which I did not believe, was nonetheless fairly close.

Interestingly, Rushton built the Wee lassie using 2 planks per side for the bottom. I found these were almost exactly parallel so I merged them into 1 plank per side. Obviously this concentrated the stresses, but the marine ply I used did not break, and glued up nicely. Rushton's original boat was built with cedar planks riveted to oak ribs; no doubt he had trouble getting the bottom shape out of one plank per side using these materials and methods.

My boats are built with chine logs: I glue the logs to the flat planks before I bend the planks. This slightly modifies the resulting hull shape as the edges of the planks stretch or compress differently with the logs attached, but so far the effect has been acceptable.

 

That's because the criterion to determine whether a surface is developable is rather strict in FREE!ship.
Surfaces like yours can not be build in steel for example without torturing the metal.

Wood (ply also) on the other hand can be forced into a not entirely developable shape in a lot of cases due to the elasticity of the material.
Theoretically developability is only a matter of mathematics (geometrical property of a surface), in practice material properties also play an important role when it comes to determining if a surface can be made from sheet materials.

 

Re. developing 3D contoured surfaces into flat panels, TouchCAD specializes in this. It's a really nice design program with hydrostatics built in.

 

Carene Software and Manual

Hi I have put Carene 2008 back up on the website it is a free download and the manual I published is in the same zip file. Enjoy
Rob

 

Thank you most kindly Sir!

Edited to add:...Slick manual. I'll have to take some time when I have it to go through it thoroughly. Thanks again.

 

Carene

Hi I do not visit the forums a great deal but if you need any help with the software I will try to offer assistance but there may be delays in my replies unless you use my contact form on the website.
Carene can do a few things that are not listed in the manual such as creating cambered deck by setting a new plank with a height of greater than half the width of the hull in all three boxes and then set the angle to 175 deg this will give you a 5 deg cambered deck that reaches the centre line of the hull.
I will post other bits of info when I can remember them
Regards Rob

 

I had number 25 in Plyboats, and did some work on one of the Betas. Recently been getting back into it. I always liked it, and came across some articles while searching for contact info, that indicated a number of big name designers that had used it. These included some personal favorites like Bo Oram, and Sam Devlin. While it is possible to come up with far better programs, if the design process is in any way connected to the reality of making boats float, I am not sure anything more than Plyboats is really needed.

Anyway. The new version of Plyboats is nearing, though if making software is anything like boats, never predict the launch date until it is wet. I hope to see it.