Transom Build Plans

[Matrim]

Evening all. Having just finished the stern post/inner post and attached to the keel I am not turning my attention to the wing transom/deck transom and 4 filling transoms. Now these appear to be complicated little beasties.

 

From a plan perspective my plans have several cutaways of what I assume is the central spine of the transom and the frame plan has what I am guessing is possibly an end point (or middle end perhaps). I also have the fashion piece marked which is the end point.

Is there a logical way to describe how to work out the correct size of one of these (once one is done the others would duplicate the approach). I am guessing construction lines projected but am unsure so looking for assistance from the plans masters out there. 

 

Once these are out of the way then the cant/full frames will fill my time for a year or 2 and Wayne Kempson's wonderful CAD drafting plan covers how to create those in details so I will be good cad wise after these are done.

 

If anyone has any pointers on how to plan one of these out then I would be grateful.

 

For those just interested but without knowledge here is a cad view of the area in question with the transoms in green and the fashion piece (I think) in pink

 

 

and from the actual plans we have the body plan

 

 

frame plan with a curious wing shape

 

 

and the internal fittings plan

 

Edited May 18, 2023 by Matrim
wasn't red was pink

[iMustBeCrazy]

On 5/19/2023 at 4:22 AM, Matrim said:

assistance from the plans masters out there

Well I'm certainly not one of them, I believe I'm further down the learning curve than you.

But since I have to do this myself sometime I had a play and this is what I came up with (not much):

 

This superimposes the frame plan (green) and the outboard profile (blue) over the inboard profile (red) and shows that the transoms are horizontal across the stern and that they are horizontal in profile except number 3 which tilts down following the lower deck.

 

Since number 3 tucks up under the lower deck, we can use the lower deck plan to get the shape of number 3.

That's about all I can come up with, hope it helps.

 

 

[druxey]

So, think of the transoms as waterlines in shape. (Yes the deck transom is canted slightly, but you can allow for that.) From the lines drawing you can develop the various waterlines for each transom, top and bottom surfaces. Yes, tedious, but that is the way to go 

[Matrim]

thanks both. That 'use the deck plan' for one of them (plus some extra for fairing) is a lovely idea. I can also then take that one and project back on the plan to see where the waterlines would be and then extrapolate the opposite for the others...

 

Crag gets extra points for using the actual plans of the ship I am building in his response (that was a surprise - I looked and thought - hold on that's my ship, I must have mis-read)

Edited May 20, 2023 by Matrim

[Matrim]

Made my first attempt at the lowest filler transom using a combination of the master plan and inner post. It helped when someone pointed out that the inside line is not terribly important as its non viewable and as long as the shape is tracked anything which might use it can then be adjusted accordingly.

 

With that said my approach was to throw constructions down to the sheer and do an entire waterline then to trim using the body to the correct size

 

 

I could then use the inner post plan to add the correct chunk for the joint and then took an approximate size for the width

 

If there is anything hideously wrong with the approach then please shriek! One curiosity Turbocad wise was that I found the control points curve was happier with this than the bezier.

 

One thing done differently to the pictures above was that the width of the joint is slightly wider than the keel so I took the start point from there in the end.

 

This piece still needs the scores for the vertical filler pieces on the bottom side (which will be done at the end). I won't start on the rest of the filler pieces until Tuesday and I think I will switch to drawing them all on the master plan mainly so I have a track of where they are (the master plan is quite large at the moment) but that keeps the parts in a consistent location.

 

 

Edited May 27, 2023 by Matrim

[Matrim]

It would be easier if I could add some extra waterlines the problem being how to draw on the sheer..

[Matrim]

Bleugh , nomenclature incorrect, it is new station lines I want... So I decided to do this so I could improve the curve. The gap between station lines on the sheer around this area of the plan is 62 inches so I added 4 new station lines beyond the last station and one more in front of it at 15.5inch gaps. (Following image shows 'new' station lines in pink with the top one highlighted in red with the vertical constructions at the waterline points made)

 

I then pushed a construction line up from the relevant waterlines and connected on the body plan to get the correct representation higher up. First image shows the same line as above generated, the lower all the new stations on the body

 

 

Now I have more lines of reference for generating the shape of the transoms on the sheer.

[iMustBeCrazy]

5 hours ago, Matrim said:

it is new station lines I want...

(Note: The drawings below are really rough)

 

It's both to give an intersecting point in space. The problem is that we know there are complex curves above waterline 5 and aft of station 29 and the plans give us no information about this area.

 

Below W4 things are pretty straightforward because we have the shapes at the waterlines and adding new station lines aft of S29 is pretty much like nailing a batten on.

 

We add in what info we have.

 

 

And here we run in to my lack of skill, Transom 3 (in blue above) should have another curve on the aft surface curving forwards at the bottom edge.

 

More importantly there is a shape, roughly an eighth of a sphere (visualise an orange cut vertically into four quarters the once horizontally giving eight "triangular" segments) with one of the points touching one of those top aft corners. (or something like that)

 

The plans give no information about this shape or how it fairs into the waterlines etc we do have.

 

Obviously the above drawing has errors, T2 is too wide t4 is too narrow and the curves aren't there.

[druxey]

You need to run additional waterlines and buttock lines here that fair with the rest of the aft hull. 

[iMustBeCrazy]

 

I'm going to have to call it a 'rounded corner', an eighth of a sphere isn't right (but that's what is shown here). However you can see where the rounded corner cuts into T4 and T5, they will have to be shaped to fit.

The rounded corner will need to follow the curve of station 29 and transom 3 will need to be extended outside the lower deck.

The rounded corner will have to have a tighter radius.

[druxey]

It's more like an inverted cone: the top edge of the wing transom should come to a point or angle.

[iMustBeCrazy]

11 minutes ago, druxey said:

It's more like an inverted cone:

A section of an inverted cone sounds like a pretty good description, but shouldn't there be some curvature to it? Perhaps a section of an inverted bullet shape?

[iMustBeCrazy]

Did anybody notice Transom 6 hiding in there?

 

Edit: added Transom 6 and Station 29.5.

 

Edited May 29, 2023 by iMustBeCrazy

[druxey]

That is the wing transom! That is the one where the upper surface comes to an angle. Below is s set of transoms for another ship. 'W' is the wing transom, viewed from above. The grey line is the lower outline of the transom. Note that conventional numbering of the other transoms is from above to below.

 

[iMustBeCrazy]

29 minutes ago, druxey said:

That is the wing transom!

Oops.

 

29 minutes ago, druxey said:

Note that conventional numbering of the other transoms is from above to below.

Doh! I blame working in 3D, it's unnatural.

 

But on the bright side, we're getting closer and I'm learning things.

[Matrim]

Thanks all, with the extra waterlines I am happily drawing out the easier filler frames first before moving to the angles on the wing/deck