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DRB
09-25-2006, 09:17 AM
I am an amature builder. I have built a couple of small boats that did not require lofting. I think that I have conviced myself that for my next project I am going to build John Gardners 16' semi Dory that will require lofting. I don't have a wood floor and I don't have very much room to work, (17 x 24) shop. I am looking for short cuts to the lofting process. Is it feasable to loft to 1/4 or 1/2 scale to insure fairness of the hull? Is there an inexpensive (simple to operate) software program that could be used to check demensions for fairness on a simple hull like this, or is lofting to full scale the only way to go? Thanks, Doug

donald branscom
09-25-2006, 09:38 AM
I am an amature builder. I have built a couple of small boats that did not require lofting. I think that I have conviced myself that for my next project I am going to build John Gardners 16' semi Dory that will require lofting. I don't have a wood floor and I don't have very much room to work, (17 x 24) shop. I am looking for short cuts to the lofting process. Is it feasable to loft to 1/4 or 1/2 scale to insure fairness of the hull? Is there an inexpensive (simple to operate) software program that could be used to check demensions for fairness on a simple hull like this, or is lofting to full scale the only way to go? Thanks, Doug

I used to just dream about having a space to work. At all.

Bruce Hooke
09-25-2006, 09:43 AM
There are a couple of challenges with lofting at half scale:

1. You can't pick up shapes directly from the lofting floor. Part of the point of lofting is that it gives you the full size shapes for various parts. Sure you could take measurements and scale up, but its more work and another place for errors to creep in.

2. Any error is doubled. If your line is off by 1/4" on the lofting floor it will be off by 1/2" on the boat.

I've heard of people lofting at full length and width but half the length of the boat (i.e., compress the frame spacing artificially). I think you still might have to loft certain parts to correct scale in all directions, but maybe not on something simple like a dory. I have no direct experience with this method of lofting.

I will say that if you have enough space to build the boat you should have enough space to loft it on a few sheets of plywood or flakeboard.

Canoeyawl
09-25-2006, 11:37 AM
I have lofted a couple of small boats to “prove” the lines by lofting the sections full size and the long lines to or scale (or whatever works!) For a sixteen-foot boat it will fit on a sheet of plywood. The lofting will look like a Guppy but it will prove the sections! On a small boat the bevels can just be cut to fit as you go using a fairing batten and the final sheer profile can be established after the molds are erected.
(It was suggested to me years ago that this lofting method was used to build ships when they did not have a loft floor several hundred feet long. I don’t know if there is any truth to this, perhaps the bevels were picked up from a scale drawing or model)
Edit to add; by exaggerating the curves of the long lines this method seems easier to visualize any errors in fairness.

mcdenny
09-25-2006, 12:08 PM
Here's the way I got the lofting off the floor (easier on my old back) plus a 4' drywall T square becomes quite handy if you are careful to get the top edge straight. Leave the plywood a little higher than the support frame to allow for trimming.

This is the second boat I have lofted this way and its a little more work as you have to construct the support frame but I think the physical comfort plus the ability to step back and get a perpendicular view of the lines is worth it.
http://www.imagestation.com/picture/sraid207/p310028f8caf518251524d4126670ead4/ee921130.jpg

http://www.imagestation.com/picture/sraid207/p9548926fd38612a26a835ba431c47d92/ee921131.jpg

http://www.imagestation.com/picture/sraid207/p1c934ec345da8193221aedbb0438111f/ee921132.jpg

I used 1/4" luan which is too flimsy to pound nails into but drwwall screws put in a few turns by hand worked fine to locate battens.

In the 25' Electric launch thread below you can see the lofting still on the wall behind the boat.

Jay Greer
09-25-2006, 12:41 PM
Denny,
I like your vertical method better than mine! In the beginning, we used the yard fence.
Jay

htom
09-25-2006, 01:43 PM
That looks very nice and handy, Denny.

DRB
09-25-2006, 06:48 PM
Thanks for the response guys. Denny, what a great idea you have. My shop has exposed frame work on the walls so it would be very easy to set this up. I also wasn't looking forward to bending over on the floor all day.The wheels are turning now, talk to you later.
Doug

paladin
09-25-2006, 07:49 PM
since I can't bend over...or get on my knees (I can, but then I can't get up) .....I did my prelims on the garage wall (drywalled) then painted over it, it needed painting anyway.....only problem was that half my nails didn't hold well for the batten....