GT 27 - Bow/Stern Transom frame positioning

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rwatson
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GT 27 - Bow/Stern Transom frame positioning

Post by rwatson »

To Jacques, or anyone else involved in the GT27 build -

When mounting stations on a strongback, every station EXCEPT the bow and stern transom have the distance to the Baseline specified on the plans. (Metric Drawing D260/4) I cant assume the bottom of the Stern Transom is the same as the preceding frames, as the plans are Not To Scale (a big dissapointment)

How do I calculate the mounting height in relation to the Bow and Stern Transom from the plans ?

All suggestions wlecome



ormet1
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Re: GT 27 - Bow/Stern Transom frame positioning

Post by ormet1 »

Have bottom panels. floor frames and stringers in place. For the moment I have let the stern transom station take up its natural position. it is my intention to let the installation of the sides and transom decide the final position and fit supports to suit (using one layer of transom only to establish fit). I have the forward position in place and will check tomorrow on how dimensions were arrived at.

Regards

Trevor (Big T)

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Re: GT 27 - Bow/Stern Transom frame positioning

Post by jacquesmm »

For the transom: the plans show the distance to station 7, the height at the keel is the same than station 7.
For the bow, we show the distance but not the height.

We could have shown it but builders did what Ormet1 does: install the side panels and then line up the "ends" with the side panels.
That gives the height and the angle.

If you want a height, for the bow, the lower tip is 6" above the BL.
If you want a drawing with angles, I can quickly produce one but the other method is much easier.
Jacques Mertens - Designer
http://boatbuildercentral.com

rwatson
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Re: GT 27 - Bow/Stern Transom frame positioning

Post by rwatson »

jacquesmm wrote:For the transom: the plans show the distance to station 7, the height at the keel is the same than station 7.
For the bow, we show the distance but not the height.

We could have shown it but builders did what Ormet1 does: install the side panels and then line up the "ends" with the side panels.
That gives the height and the angle.

If you want a height, for the bow, the lower tip is 6" above the BL.
If you want a drawing with angles, I can quickly produce one but the other method is much easier.
Thanks for that Jaques. I can live with that information. True, the stern looks like it is placed the same as station 7, but since the plans are NTS, one cant assume anything. Also, if station 5 is 245cm below BL, and station 6 is 242 below BL, and station7 is 241 below BL, having the transom also at 241 also means you disrupt the curve of the keel, which I wouldnt have expected. It certainly doesnt show on an A3 page.

I can (and did) work out the angles of the bow and stern with a bit of trigonometry, as the distances from vertical are there as you say.

With the bow, I wouldnt rely on using the sides as a guide, too many chances for innacuracy ( even Ormet is unsure) - and if I am building over a frame, (as is recommended for the most accurate method) one would certainly place the bow in position well before the sides. I will place the bow transom 15.24 centimetres above the waterline, and see how it looks.

I think for the little extra effort to amend the plans with waterline and angles, it would save a lot of future annoyance. As it is, I am reading the station offsets into Delftship to produce a Cad image to check the fairness. This will also provide me with an easy to interrogate source of dimensions if I need to get other measurements.

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