How to Match a Curve?

Sonrisa · 08-02-2010, 22:45

Hi All,

I've had to do this several times to build shelves etc. Try to cut a board that will fit nicely against the totally irregular curve of the hull. I need to do it once again, and am wondering if anyone out there has any tips to make this easier.

How do I map the curvature onto a board which I can then cut to shape?

Thanks.

johnar · 08-02-2010, 23:04

scrib it on the board or paper, make paper cut out first.

Dutch

johnar · 08-02-2010, 23:14

This should show you how. Holder 12

bewitched · 08-02-2010, 23:15

Get someone to hold the board you are about to cut against the curve of the hull.

Take a block of wood a bit longer than the largest gap between the hull and the board

Run the block along the hull while holding a pencil against the other end - the pencil drawing a line on your board.

cut along the pencil line

nigel1 · 08-02-2010, 23:27

Depending on how long the curve is, you can use a Profile Gauge

**Boracay** · 09-02-2010, 00:28

I've found that accurate measurement and oversize cutting followed up by trial and error fitting does a passable job.

For really tricky bits I like to use scrap to make the ends or corners and then screw together a temporary template.

If I really need something to fit well I take the passable piece and use it as a template to do a tight fitting job. It's another reason why I like to work with pine.

Life's too short to do everything perfectly on a big boat.

frstjump · 10-02-2010, 06:32

Check out the tick-stick shown Wooden Boat Renovation by Jim Trefethen

**James S** · 10-02-2010, 06:53

You can also eye ball it cut the cardboard semi close...then cut a bunch of smaller pieces of thin stuff like poster board (or even paper if your close enough), sliding them over the main piece until they touch the shape then tape them down....one after the other..like a dashed line.....lots of time can be wasted trying to make the template from just one piece....it can be a hundred pieces taped together.

Randy · 10-02-2010, 07:23

How complex is the curve?
Like a lot of these guys are saying you need a template and for complex shapes get 1/8" door skin at Home Depot, rip it into 2" wide strips, cut these strips into lengths short enough to work with individually that you can scribe as sections and while they are in position use hot melt glue to fasten the adjacent pieces together. If the template gets too large or cumbersome make it as 2 or 3 sections that are labeled to reassemble at your work area.

SabreKai · 10-02-2010, 09:57

I had to repair part of the counter top on Espie, as it had rotted out. The PO had cut away the bad material, and left an odd shape. A parallelogram with one long side curved to match the hull.

I took my carpenters square, and drew a line at 90 deg to the aft bulkhead, and then drew a series of lines parallel to the aft bulkhead spaced 2 inche apart. Then I just measured the offsets at each parallel, recorded them and transferred them to the plywood. Cut it out with the band saw and did a trial fit. Took off a couple of high points with my angle grinder and a sanding disk. I then went along the entire hull side edge and beveled it to fit. Drop in piece fitted perfectly.

Sabre

pwratch · 10-02-2010, 10:35

Google "tick stick". Old (and young) boat builder technique. Works great. Won my lunch a few times when building houses.

Joli · 10-02-2010, 10:36

I've found the best way to make shelving is to use thin wood strips tacked together with a hot melt glue gun. Scribe the curve as others have said, then remove the one assembly you've glued together and trace to a board.

pwratch · 10-02-2010, 10:44

Google "tick stick". Old (and young) boat builder technique. Works great. Won my lunch a few times when building houses.

**James S** · 10-02-2010, 10:48

Quote:

Originally Posted by pwratch

Google "tick stick". Old (and young) boat builder technique. Works great. Won my lunch a few times when building houses.

Its also know as a "joggle stick"

dohenyboy · 10-02-2010, 18:42

Quote:

Originally Posted by Randy

How complex is the curve?
Like a lot of these guys are saying you need a template and for complex shapes get 1/8" door skin at Home Depot, rip it into 2" wide strips, cut these strips into lengths short enough to work with individually that you can scribe as sections and while they are in position use hot melt glue to fasten the adjacent pieces together. If the template gets too large or cumbersome make it as 2 or 3 sections that are labeled to reassemble at your work area.

this is how I have seen it done by professional marine carpenters

08-02-2010, 22:45	#1
Sonrisa Registered User Join Date: Dec 2009 Location: Vancouver BC Boat: 1978 Pacific Seacraft Mariah 31 Posts: 22	How to Match a Curve? Hi All, I've had to do this several times to build shelves etc. Try to cut a board that will fit nicely against the totally irregular curve of the hull. I need to do it once again, and am wondering if anyone out there has any tips to make this easier. How do I map the curvature onto a board which I can then cut to shape? Thanks.

08-02-2010, 23:27	#5
nigel1 Registered User Join Date: Oct 2009 Location: Manchester, UK Boat: Beneteau 473 Posts: 48	Depending on how long the curve is, you can use a Profile Gauge __________________ Nigel Beneteau 473 Manchester, UK

09-02-2010, 00:28	#6
Boracay Moderator Moderator Join Date: Feb 2004 Location: nr Blackwattle Bay,Sydney, NSW, Australia Boat: Steel Roberts Offshore 44 Posts: 2,156 Images: 7	Trial and error... I've found that accurate measurement and oversize cutting followed up by trial and error fitting does a passable job. For really tricky bits I like to use scrap to make the ends or corners and then screw together a temporary template. If I really need something to fit well I take the passable piece and use it as a template to do a tight fitting job. It's another reason why I like to work with pine. Life's too short to do everything perfectly on a big boat. __________________ Rust never sleeps Boracay Blog.

10-02-2010, 06:53	#8
James S Moderator Moderator Join Date: May 2008 Location: I live in Yemen...the boats in Lebenon Boat: 1978 CT48 Arctic Lady Posts: 1,916 Images: 125	You can also eye ball it cut the cardboard semi close...then cut a bunch of smaller pieces of thin stuff like poster board (or even paper if your close enough), sliding them over the main piece until they touch the shape then tape them down....one after the other..like a dashed line.....lots of time can be wasted trying to make the template from just one piece....it can be a hundred pieces taped together. __________________ James S/V Arctic Lady (Few things should be taken more seriously than pleasure)

10-02-2010, 09:57	#10
SabreKai Registered User Join Date: Sep 2008 Location: Toronto, Canada on Lake Ontario Boat: Roberts Offshore 38 Posts: 319	I had to repair part of the counter top on Espie, as it had rotted out. The PO had cut away the bad material, and left an odd shape. A parallelogram with one long side curved to match the hull. I took my carpenters square, and drew a line at 90 deg to the aft bulkhead, and then drew a series of lines parallel to the aft bulkhead spaced 2 inche apart. Then I just measured the offsets at each parallel, recorded them and transferred them to the plywood. Cut it out with the band saw and did a trial fit. Took off a couple of high points with my angle grinder and a sanding disk. I then went along the entire hull side edge and beveled it to fit. Drop in piece fitted perfectly. Sabre __________________ SabreKai SV Sabre Dance, Roberts Offshore 38 SV Espina, Mason 31

08-02-2010, 23:04	#2
johnar Registered User Join Date: Mar 2008 Boat: Morgan, O.I. 33' Dutch Treat Posts: 376	scrib it on the board or paper, make paper cut out first. Dutch

08-02-2010, 23:14	#3
johnar Registered User Join Date: Mar 2008 Boat: Morgan, O.I. 33' Dutch Treat Posts: 376	This should show you how. Holder 12

08-02-2010, 23:15	#4
bewitched Registered User Join Date: Sep 2009 Location: S.E. Asia Boat: Catalina 42 Posts: 245	Get someone to hold the board you are about to cut against the curve of the hull. Take a block of wood a bit longer than the largest gap between the hull and the board Run the block along the hull while holding a pencil against the other end - the pencil drawing a line on your board. cut along the pencil line

10-02-2010, 06:32	#7
frstjump Registered User Join Date: Dec 2007 Posts: 5	Check out the tick-stick shown Wooden Boat Renovation by Jim Trefethen

10-02-2010, 07:23	#9
Randy Registered User Join Date: Oct 2008 Location: San Diego Boat: Searunner 31 Posts: 391	How complex is the curve? Like a lot of these guys are saying you need a template and for complex shapes get 1/8" door skin at Home Depot, rip it into 2" wide strips, cut these strips into lengths short enough to work with individually that you can scribe as sections and while they are in position use hot melt glue to fasten the adjacent pieces together. If the template gets too large or cumbersome make it as 2 or 3 sections that are labeled to reassemble at your work area.

10-02-2010, 10:35	#11
pwratch Registered User Join Date: Mar 2007 Posts: 20	tick-sticking Google "tick stick". Old (and young) boat builder technique. Works great. Won my lunch a few times when building houses.

10-02-2010, 10:36	#12
Joli Registered User Join Date: Nov 2005 Location: Ohio Posts: 1,841	I've found the best way to make shelving is to use thin wood strips tacked together with a hot melt glue gun. Scribe the curve as others have said, then remove the one assembly you've glued together and trace to a board.

10-02-2010, 10:44	#13
pwratch Registered User Join Date: Mar 2007 Posts: 20	tick-sticking Google "tick stick". Old (and young) boat builder technique. Works great. Won my lunch a few times when building houses.

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