# Thread: Missing offset on Tom Cat plan...

1. Member
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Anybody building the Tom Cat from full set of plans? I'm using the plans from the book ( The Making of Tom Cat - by William Garder) and there seems to be 1 missing offset - for butt 24" at frame 1. I'm hoping maybe the full set has that.
Any help would be appreciated.
Thanks!

2. Okay Im gonna dare to put me nose in here

But you say there is 1 missing offset at "butt 24" at frame 1" right?

Have your drawn it out? how have you come by there being one missing offset?

If youve drawn it out even 1/2" to 1ft and found tbere is one number missing or wrong from what Ive heard and understand this... and we are only talking about one number... or if youve drawn it to size and only one number is missing then use your lofting batten and lay it between the nails and so make it fair.

Ive also found on some plan sets that the designer has made a wrong offset ie: say the number is meant to be 1 4 5 and yet when you lay it out the designer has instead written 1 8 4 at that point... but you know that the other numbers either side are right and lay in the appropriate places... lay your batten out and make the line fair between the two correct points ... the batten will lay fair between the two nails either side that then becomes the reference offset that was wrong ie: the 1 4 5

If its not there at all... then again lay the batten between the two known reference points and the batten will lay fair the missing offset number can now be gotten from the lay of the batten.

But I am not an NA or a designer and may well be wrong... the least I am doing is keeping your thread at the top and giving food for thought...

Cheers!

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I am lofting this out full size. Started this morning and for all the looking these over never noticed:
How to I get the points where butts 12" and 24" touch the sheer in the front half? Hope you can see it here:

Actually, I think butt24" meets the sheer right at station 1 - it's butt12" that's the stinker.
I think the closeness of station 4 to the transom will give me points from the long batten.
This is my first lofting...thanks all!

[ 08-28-2005, 01:33 PM: Message edited by: SparkG ]

4. Take the following with a HUGE grain of salt, as I'm still on the learning curve when it comes to lofting.

In answer to your first question, it doesn't look like you need the offset for BUTT 24 at Sta. 1. You've got the shear height and halfbreadth, waterlines A, B, and C, the rabbet, and BUTT 12. Using your batten, these should be enough points to draw in the curve.

On your second question, use the same technique. You've got points for the stem height, and the shears at Stas. 0, 1, and 2. Spring a batten between these points and you'll get the shear heights at BUTTs 12 and 24.

5. From the lines drawing, it appears that the missing number nearly coincides with (is within a couple of inches of) the height for the sheer at frame 1.

Draw it out using the height and half-breadth for the sheer at frame 1, ignoring the height for butt 24". Trying to plot another point so close to the other will be no help and may just muck things up.

Wayne

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Thanks for the input guys...I'm still staring this over...I did loft out the body plan (just stations 0, 1 and 2 and it may give me what I need...not sure, had to break for bbq and beer 'til next weekend
What I'm looking to do is loft this out full size, then mark it off every foot in the profile lofting, take measurements with a new set of offsets for 12 or so stations and cedar strip this hull with 3/4" x 1/4" cove and bead and go from there.
I have a 4' x 16' lofting surface. Over that I have very large pieces of thick mylar (I can get this easily where I work) So I'm lofting it out on that so 1) I don't have to cut up my lofting 2) I can see through the mylar for making the stations and parts 3) I don't have to go through this again 4) should make it easier to make modifications.
Any way, the body plan of 0, 1, 2 stations are done, the profile is laid out and the sheer and keel are marked off and, I had a 100% of the stem that I laid up under the mylar and marked off. Just need to get these other lines marked off so I can take the new/extra station mesaurements.

[ 08-28-2005, 08:34 PM: Message edited by: SparkG ]

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Answering myself...I think I got it...I lofted out the sheer line of the plan view and got what I needed. Now I can see just where butts 12 and 24 cross the sheer...I think!

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Looking at some of Mr. Garden's published plans, I think he leaves more things to be measured off the drawings (i.e. doesn't note the dimenstion on the plans) than the average designer. Due to its sharp curve, the buttock is not too useful for fairing in this example, so he may have considered that HE would not use it to loft the boat, so he omitted it from the table.

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I'm beginning to agree with that PVanderwaart...Wild Dingo - I see you smirking at me over in the corner there! LOL.

[ 08-30-2005, 08:43 PM: Message edited by: SparkG ]

10. HEY!! Wasnt smirkin Not me!!... I was merely smilin that yer got it yer ownself!... means congrats cool one excellent whatever... means in Aussie speak bloody good on yer mate!

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I know Wild Dingo - I was just kiddin ya' - glad you guys jumped in to help me out...sure I'll have more questions before this lofting is over.

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Actually, B24 terminates at the sheerline just forward of station One. I think Mr. Garden may have ommitted the hieght number of B24 at station one because that hieght is so close to the sheerline, the hieght of which has already been established. -Just a guess. By the way, you sure did pick a pretty one. Keep us updated with construction picks!

[ 08-31-2005, 01:59 PM: Message edited by: Stephen Hutchins ]

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Also just curious, do the plans have lines for an expanded transom? (Inside/outside faces?)

[ 09-01-2005, 06:55 PM: Message edited by: Stephen Hutchins ]

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It's a curved raked transom Stephan...I'm still studying it...kind of jives up with the article this WoodenBoat issue - "Raked Curved Transom - Just Build it"...Gardner show the jig for making this curved raked transom...
BTW...I did see that B24 ended just forward of station 1, but when I put a batten on the marks for the profile with b24 from the offsets it didn't come close to the sharp upsweep shown in the plans. That's when I decided I needed to loft out wl's A, B and C - that will give me those crossing points that aren't in the offsets...am I putting that right?

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Yeah, that last question should have been worded: "Do the plans have expanded lines for the transom?"
About B24: you might also need to use a tapered batten in order to make that curve. Enjoy.

16. This might be a little late, but I'm reading Greg Rossel's "Building Small Boats." It has a very good chapter on lofting.
Al

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