Lofting question

[sryan]

I'm lofting a 26 ft single chine vhull powerboat and the plans show the measurements for 7 stations with a frame at each station. The plans also show frames between each station, but no measurments. How do I determine the size of the frames between the stations using the data I have? Thanks!

[Jim Ledger]

Loft the boat completely in the usual manner with the stations you were given.

Afterwards, draw perpendiculars on the profile where you want the frames, along with corresponding lines on the plan view.

The fore and aft lines, sheer, chine and rabbet in this case, passing through these straight lines will give you the dimensions you need to construct additional stations on the body plan.

If this is not clear, let me know and I'll try to explain further

[sv Lorelei]

Unless otherwise specified or drawn on the plans, they should be the same dimensions as the station frames. Knowing the boat and the designer might be useful to determine for sure as different designers tend to draw plans ...well....differently.

[Jim Ledger]

Unless otherwise specified or drawn on the plans, they should be the same dimensions as the station frames. Knowing the boat and the designer might be useful to determine for sure as different designers tend to draw plans ...well....differently.

You must be speaking about the size of the frame components. As I understood the question the difficulty lay in determining the outline of the intermediate frames actual shape, which will change with any change in fore and aft placement.

[sv Lorelei]

How do I determine the size of the frames between the stations using the data I have?

Jim. I think you could read that either way. You did a fine job of answering it if it was interpreted as How do I determine the location of the additional frames. I was just hedging that with a response to a more literal translation in case that was what was needed as well. In either case I think the bases are covered ;-)

Tim

[crawdaddyjim50]

Bases covered. Tim you are refering to the "scantling" size correct. Which would be the same as the adjoining frames.

Once the boat is completely lofted the measurements of all sorts of undefined parts can be worked out. This is done to clean up the plans and to help reduce confusion. Which can be considerable if this is your first lofting.

If it is. Please try to find Chapelle's book and use it to answer questions as you go along. There are a few good books on lofting but to be sure nothing beats doing it to make it understandable.

Anything not clear in the books will be answered here by some of the best people I know of.

Jim

[sv Lorelei]

Bases covered. Tim you are refering to the "scantling" size correct. Which would be the same as the adjoining frames.


Exactly. Unless it was specified as different. For example, many of Wm. Atkin's bigger boats were spec'd assuming doubled sawn frames at the stations and steam bent single sized in between added afterwards....but you get that from the drawings and notes. In that regard...no lofting of the added frames required. Everyone has a wrinkle on drawing a boat but if you live with the plans long enough, it all works through.

.....Frame On!

[sryan]

Thanks everyone. The first time is always the most difficult and your comments are very helpful.

Stu

[SamSam]

I'm lofting a 26 ft single chine vhull powerboat and the plans show the measurements for 7 stations with a frame at each station. The plans also show frames between each station, but no measurments. How do I determine the size of the frames between the stations using the data I have? Thanks!

You get the measurements you need from your lofting. That is the purpose of lofting, to refine lines and give you an actual shape to take dimensions from. Even the measurements you are given on the original 7 stations may change, depending on how the lines fair out. Sometimes measurements are given wrong or typo's occur. How the lines fair out depend on the quality of battens you use, and how careful you work.

[mcdenny]

Sam makes an important point - the measuerments given on the plans for the stations ARE NOT necessarily the dimensions to make the frames. The fairing process will cause some small changes in the waterline and/or buttock lines. These faired lines define the shape of the frames (probably less planking thickness).

You probably knew that but...

[crawdaddyjim50]

Reported to Scot


reported what to scot? Don.

[Don Z.]

There was some spam there... looks like Scot took it away already...