How do you draw missing templates from a two view plan?

[Will Mason 1Participant @willmason1]

Hi folks, could someone explain to me please, how do you work out and draw templates for bulkheads etc, from a plan that has only two views?

I have a few boat plans, such as Aerokits ones which as many of you will know have only 2 views and have no bulkheads etc shown on the plan.

Is there a relatively easy way of drawing these templates from a 2 view plan or can anyone point me towards an example/description of how to do this please?

I have seen one where you draw a line at what appears to be 45 degrees, starting above the end of the upper view and you draw lines out from reference points on that view. You also do the same from the lower view (if that makes sense) but I have no idea if that is a good way or if there is a better/more accurate way to achieve the end result.

Also i am aware that there are templates floating around for quite a few of the Aerokits range, but I would still like to have a go at drawing some myself, so that I know how to do it for future reference.

Thanks in advance

Will

[Will Mason 1Participant @willmason1]

[Ray Wood 3Participant @raywood3]

Hi Will,

By chance I'm drafting the bulkheads for Sea Queen, I built one in the 70's from the original Aerokit version and again 5 years ago from the Jontika kit, sold them both,  but still enjoy building them

Assuming you have the top and side views, you will need paper large enough for the whole bulkhead , the base line at the base of the keel is the line to measure from for all the side views, a good size set square is a good starting point to draw the centre line vertically, don't think of a boat shape all for are plotting is the locations of the deck edge and the point of the chine where the side meets the bottom. The base of the keel is usually lower than the bottom skins meet it, accurate measuring and keeping the bulkhead fully symetrical to the centre line. I quite enjoy drawing bulkheads as you can think through the building sequence as you go.

Let us know how you get on.

Good Luck Regards Ray

Edited By Ray Wood 2 on 27/02/2022 09:01:50

Edited By Ray Wood 2 on 27/02/2022 09:03:37

[Richard SimpsonParticipant @richardsimpson88330]

You are quite right that you use a process called "projecting" to give a third view from two existing views. Rather than try to explain it this web page does a pretty good job. We used to do exercises at school to generate full views of slices through a cone, which were really interesting to draw. I can remember the three types of slice were hyperbola, parabola and elipse!

This explains better than I could:

Projection Explanation

[Will Mason 1Participant @willmason1]

Hi Ray, that makes sense to me.

When you take a line from a reference point, how do you make sure that the line is perfectly horizontal from the reference point on whichever view you are taking them from?

On the example I have attempted using the 45 degree line, it was easy enough to take a line along the centre of the top view and then a 90 degree line to that, down where it meets the 45 degree line and on passed the keel of the side view, so that gave me a good central starting point. It also meant it was easy using a square onto that vertical line, to make sure that the vertical lines were actually vertical.

Does that make sense, it does to me, sort of.

Will

[Ray Wood 3Participant @raywood3]

Hi Will,

If you have a full blown drawing board projecting lines accurately etc isn't to hard, but your only measuring from the side and top views with a ruler or dividers, you are not trying to create a 3D image which Richard is suggesting.

When I had a fullsize drawing board in my workshop it had parallel motion, basically a horizontal ruler controlled by cables and pullies to transfer horizontal lines anywhere on the drwing and a base for your set square to draw accurate vertical lines, but it got in the way and I sold it !

We are only creating a 2D image for a flat bulkhead.

I use a MDF board with the paper taped on as my drawing board these days to the bottom of the board is you reference datum and use a steel rule to transfer a parallel line across the base of the drawing.

This is the Les Rowell drawing from the Aerokits version

Which boat are you building ??

Regards Ray

Edited By Ray Wood 2 on 27/02/2022 11:50:54

[Will Mason 1Participant @willmason1]

Thank you very much Richard, I will check that link out on the laptop a bit later, it will be easier to see on there rather than on my phone.

—

Cheers again Ray. I will have to see if I have a board big enough to attach a copy of the plan to.

I did have a go using the method that I described on the laptop, with an electronic copy of the plan. I though that in general it worked quite well, but I wasn't 100% sure if I had got them right or not. They do look generally correct, tome at least.

Will

The boat myself and Zooma are going to be building (one each) is a Lesro Stiletto. I have managed to get a copy of the plan, but like an Aerokits one, is side and top views only.

[Richard SimpsonParticipant @richardsimpson88330]

This reminds me of a puzzle I learned at school, so for all of you who like your technical drawings and enjoy a puzzle:

The drawing shows a front elevation and a side elevation, you simply have to complete the drawing by adding the plan.

Edited By Richard Simpson on 27/02/2022 13:21:14

[Dave Cooper 6Participant @davecooper6]

Hi Will,

There is another process called "Lofting" that you may wish to read up on. It's probably more suited to 3D modelling though (and, is also the traditional way the shipwrights of old did it…).

If you don't have a drawing board, but are into CAD, you could try Google 'Sketch-up'. This quite good enough for 2D templating given a set of reference points.

I quite often rough out my stuff using MS "Paint" (comes free with Windows and has basic drawing facilities). After this, I use good 'old-fashioned' card templates before going to wood.

Hope this helps,

Dave

[Will Mason 1Participant @willmason1]

Posted by Dave Cooper 6 on 27/02/2022 17:38:34:

Hi Will,

There is another process called "Lofting" that you may wish to read up on. It's probably more suited to 3D modelling though (and, is also the traditional way the shipwrights of old did it…).

If you don't have a drawing board, but are into CAD, you could try Google 'Sketch-up'. This quite good enough for 2D templating given a set of reference points.

I quite often rough out my stuff using MS "Paint" (comes free with Windows and has basic drawing facilities). After this, I use good 'old-fashioned' card templates before going to wood.

Hope this helps,

Dave

Hi Dave,thanks for your reply and the info.

Lofting, I've never heard of that before. I'll do some reading.

I have got sketchup on the laptop, but have never done very much with it to be honest, so my skills on it arent very high.

The attempt that I did, I used PowerPoint and the templates looked to be close, which I was pleased with for a 1st attempt.

With sketchup, do you just take measurements off the plan and transfer them onto whatever CAD program you use, or do you convert the electronic plan to a file type the program accepts and open it on there?

Will

[Dave Cooper 6Participant @davecooper6]

Will,

I think I would start with drawing a waterline (usually shown on most plans). You can then measure up and down from this reference to deck and keel level. Do this for each 'station' (bulkhead).

In plan view, the reference is the keel centreline – measure out to the gunwale /chine line for each bulkhead. You can use a pair of dividers for this (school geometry set !).

Using CAD, you need only draw one half-bulkhead then do a 'mirror image' for the other half.

Probably best to practice first with a simple box /rectangular structure until you get the hang of it. Number the bulkheads as you go to keep track and work out where you need 'holes' for motors, batteries etc.

Sorry, I've not tried importing into Sketchup but, a quick trial won't do any harm ! You could always build a scale keel and bulkhead mock-up in card /balsa as a check….I did this for the pilot cutter.

Good luck,

Dave

Edited By Dave Cooper 6 on 27/02/2022 21:29:02

[Will Mason 1Participant @willmason1]

Thanks for that Dave, I'll give it a go and see how I get on.

Will

[Chris FellowsParticipant @chrisfellows72943]

Hi Ray

I had a parallel motion drawing board on a stand that I used a great deal over my working life but approaching retirement and starting to use a drawing program on the PC I stopped using it.

Like you it used to get in the way but I was loathe to get rid of it. But eventually I removed the stand which went down the tip and removed the parallel motion. I've kept the drawing board though, even though my wife keeps asking why!

Chris

[Ray Wood 3Participant @raywood3]

Hi Chris,

Yes I had the full Monty balanced board on a heavy duty stand, I miss it now but like an exercise bike in the spare room it just was used to hang things on !! or another work bench .

Regards Ray

[Dave Cooper 6Participant @davecooper6]

I've still got mine too. It's 'A2' size with a folding frame and has a parallel motion system (pulleys and wires).

Just fits in my art cupboard – with a bit of a squeeze – and gets an airing about once a year. Somehow, I can't bear to part with it !

For small stuff though (eg A3/ A4 size), I use W H Smith's printed Graph paper pads.

Regards to all,

Dave

[Will Mason 1Participant @willmason1]

Starting with the waterline is another way, I'll give that one a go too.

I do want to have a play around with Sketchup, so I will definitely be seeing if I can use that too.

Thanks Dave.

[Chris FellowsParticipant @chrisfellows72943]

Go on then Richard, what's the answer?

I haven't tried drawing it, which I suppose I should, but I have a curve or triangle somewhere in mind for part of the plan.

Chris

[Ray Wood 3Participant @raywood3]

Hi Richard,

Yes, what's the answer ?? rather to much like being back at school for me to ask

Hi Will – As long as you have a datum of some sort as a constant reference point to use it works and the bulkheads are normally vertical to it .

Regards Ray

Edited By Ray Wood 2 on 03/03/2022 09:52:25

[Dave Cooper 6Participant @davecooper6]

Ray makes a good point about the 'verticality' of the bulkheads relative to the waterline.

However, if you look at his post about the "Sea Queen" (side view), whilst the aft bulkheads are 'normal' to datum, the bow one's are not *.

So, you may need a 'fudge' factor here (or, measure the angles perhaps) to get the bulkhead height right.

Personally, unless there's a good reason to do otherwise, I would make them all 'normal' ie at 90 degrees for simplicity of design and construction.

Dave

ps * There could be some camera 'distortion' here which is affecting things ! 

Edited By Dave Cooper 6 on 03/03/2022 11:38:38

[Richard SimpsonParticipant @richardsimpson88330]

OK guys here you go, the thing that trips most people up is not relating square shapes to two views of a circle. There is a variation with an elipse but the circle is a lot easier to sketch with a basic drawing package!

You can also do it with the height the same as the diameter so the front and end elevations look like a square.  Consequently people cannot get a cube out of their minds!

 

Edited By Richard Simpson on 03/03/2022 11:37:37

[Chris FellowsParticipant @chrisfellows72943]

I've had a quick sketch and this is all I can come up with.

Chris

[Chris FellowsParticipant @chrisfellows72943]

Posts overlapped! Mine works as well!

Chris

[Richard SimpsonParticipant @richardsimpson88330]

That works equally well Chris

[Richard SimpsonParticipant @richardsimpson88330]

Sorry I added the wrong drawing as the solution, this is the correct one:

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