Full size patterns or 'lofting' for steel boat?

[Luc N]

I am considering building a steel displacement motorboat.
The 'Mackerel 29' pleasure trawler version from www.bodenboatplans.com looks very interesting to me. I am a welder/metalworker and can work from a decent drawing but this boat needs to be 'lofted', does not have full size patterns. I have never built a boat before and I am somewhat afraid of this 'lofting' thing. I'm not a rich man and the possibility of expensive mistakes is definitely there!

Boden says on their website : 'a simplified table of offsets such that the only full size drawing or lofting that is required is for the transverse sections and stem profile'.
Is it that simple?

I can't find a similar design (under 30 feet), with (or without) full size patterns, anywhere.
This is an economical displacement boat, fairly heavy, and an all-steel(!) vessel.

Some advice would be welcome.

Thank you.

[SplineWeights]

Don't be afraid of lofting... It is not that hard to do at all. Recommend reading a book on lofting. It is really nothing more than placing dots out in reference to a line and then connecting the dots by use of splines and spline weights inoreder to get a fair line,

Hope this helps

[yago]

[quote=Luc N]Boden says on their website : 'a simplified table of offsets such that the only full size drawing or lofting that is required is for the transverse sections and stem profile'.
Is it that simple?
QUOTE]
Very simple... it just means that you have to draw the frames full size on some steel or plywood plate.
"Lofting" as it in traditional and round chine construction, often wood, means that you have to draw the entire boat with waterlines, buttock and diagonals first at size 1:1 so that then from THERE you will take the measurements for the frames... that indeed is work intensive. It's also a pleasure though.. lots of sweet curves, drawn with long flexible battens until the artists eye is pleased

In your case, it's the frames and their spacing that defines the form, so there is no "full" lofting required because the dimensions are supposed to be in the table of offsets (a grid that gives you the distances of points on your frames to the vertical centerline and the waterline).
if the boat is hardchine, that is VERY simple, you only need the top (sheerline), each chine-corner and the bottom on the centerline so usually you will have just 3 or 4 points per frame that you then line up with a straight rule.

Don't be afraid, we are with you - just go and do it!!!

[Thunderhead19]

There are some great books dedicate to this subject. Ship and aircraft lofting and plate development might be useful to you. www.metalboatkits.com has some good options for you. They require no lofting at all, even though you supply the materials.

[Wynand N]

Rather loft...

[ARGO]

I loft out my frames on the computer and get them water cut. It saves my back and knees.

[FAST FRED]

"loft out my frames on the computer and get them water cut. It saves my back and knees.
__________________
Jason

If the designer can provide a good set of plans many times having a steel supplier do all the cutting , costs no more than doing it yourself.

Their sheets are very large , and the computer places all the cuts very efficently , and they can recycle any scrap .Accurate too!

Might be worth a look.

FAST FRED

[hoagey]

I am going to purchase plans for a small aluminum boat and try my hand at building. The CNC files are not available, but the designer has said I may develop the files if I want to. I think it would be exciting and fun to learn how this is done.

My question is how I go about transfering the the plans to CNC files.

Any help would be appreciated.

Thanks, Hoagey

[ARGO]

It just so happens that this is part of what i do. Send me a line