Shortening Chamberlain Gunning Dory

[Gary Davis]

Greetings from Montana.

I'm still debating which boat to build as my first. I've ordered Oughtred's Amberjack plans (should be here any day) and am still considering Gardner's modified Swampscott and Chamberlain gunning dories. Of what consequence would it be to shorten the gunning dory, as described by Gardner, from 18' to 17' so that I could build it in my garage and still be able to close the door?

If shortened a foot, can the frame dimensions remain "as is" to maintain as much beam as possible?

Other than some lofting, would building one of the Gardner boats be significantly more difficult than the Amberjack for a first-time builder?

Thanks in advance for any advice and suggestions.

Gary Davis

[kenjamin]

Trust Iain Oughtred. He knows of what he speaks. Here's his discussion of the Amberjack design:

"These light dories have quite a lively performance, especially under sail: the extra reserve stability of the rounded sides helps the sailing ability, handling and safety. However a dory is primarily a rowing boat, and no compromise is made of the superb handling under oars. Attempts to design "sailing dories" end up losing the style and character of the true dory." – Iain Oughtred

The Amberjack built as per plan will be a fine boat and worth more when you sell it to help finance your next build. Please note, however, that when it comes to modifying plans to suit personal wants or needs, the person offering you this advice is one of the worst sinners.:o

[Thorne]

Can you tell us what the primary function of the boat will be -- rowing, sailing, motoring? Secondary propulsion being oar or motor? Standard number of crew?

As for the length issue, that is hard to say. I tried figuring out how long of a boat I could build or restore in my garage and was off by several feet. You need to consider the size of the building frame or trailer, and access around the ends of the boat.

I'd be tempted to build something that will fit, particularly if sailing will be a primary use, as a shorter boat can carry more cargo and crew under sail. The length of the gunning dory is primarily due to its pulling boat focus, where waterline length = speed and efficiency.

[Ian McColgin]

For the gunning dory, there are two ways you could do this.

One is to shorten the interval between frame stations to about 94% of drawn. She'll be a hair plumper but should sail and row well enough.

The other approach might be to keep the stations as is but put some curve into the stems from a bit over half way up the garboards, taking about 6" off each end. This may leave her a little snubby looking - the ends as drawn are not just lovely but handle big water well - but keep the water lines fully intact.

Better would be to build on a diagonal in the garage and plan on lots of annoying scrambling since you really need at least 4' past the LOA to give a couple feet squeeze by room at each end.

Or raise the garage door and put up a polytarp barrior to extend the space.

Or (I did this with a mast) modify the garage door to let the stickwork out where needed but you can open the door to work, though here for boatbuilding you'll still need some sort of portable shelter for the boat.

Or find a design you like that really fits your work space.

G'luck

[Thad]

In the book Wooden Boats to Build and Use, Mystic, John Gardner shows the plans Walter Wales drew for Gerald Smith's 17' version of Chamberlain's 19' Gunning Dory. It, as the larger one, is a great rowing boat, light and subtle.

[Gary Davis]

Thanks for the quick responses.

I need to measure my garage again (on the diagonal) to see what I can truely accommodate in there. The door has to close - this IS Montana. The tarp extension would never get past my wife. Once built, it will live outside, under cover, on a trailer.

I have Gardner's last book, and I'll look at it tonight for the 17-footer. Any obvious differences other than the length?

My intent is to sail, drift, and row - in that order.

Is there someplace to go to learn how best to develop a materials list?

Gary

[Ian McColgin]

If you use modeler's balsa to make a model - I like 1-1/2" to the foot as then 1/8" represents an inch - you'll be easily able to pick the model planks off and compare them to scale representations of plywood (don't forget that you loose wood length with each scarf) to layout the planking and bottom most efficiently. I don't remember for sure - it was '75 when I built her, but I think Leeward (Chamberlain 18' gunning dory) consumed 5 sheets - three scarfed together for the shear and mid strakes with the bottom gotten out between, and two scarfed together for the garboards.

The wood for frames and stems and gunnels and such is easily figured right from the plans.

G'luck

[Thad]

Gerald's shortening of Chamberlain's GD was done using Chamberlain's frame molds. He shortened the length in order to keep the original shape and proportion but need a bottom board that was available, less than the 20+" width needed for the bigger boat. I built one and installed a rig very like the one Gardner drew for his model, different in that the trunk was kept at thwart level so as not to grind into the rowers tail bone, with the board narrower to fit. I am not a fan of Gardner's modification, symmetrical fore and aft it loses the subtle power and grace of Chamberlain's design.

[Gary Davis]

Hey Thad,

Help me understand how Chamberlain's boat is asymmetrical fore and aft.

Thanks - Gary

[neilm]

Chamberlains original 19fter is narrower in the front half.

I think you are fine shortening a Gunning Dory. My CLC Skerry is basically a 15ft Gunning Dory and it's very seaworthy.

Neil

[Thad]

Chamberlain's is far from symmetrical. Gardner took off from Chamberlain's design and drew or modeled a hull symmetrical fore and aft, so it could be lofted half length. Chamberlain's bow is full low and tighter high relative to the stern which is finer low and fuller as the topsides come around to the stern stem.

[Gary Davis]

Thanks Chad.

And the reason for the asymmetry in the original is . . . . ?

Gary

[James McMullen]

My intent is to sail, drift, and row - in that order.

Then you're picking the wrong design, my friend. Both the Amberjack and the Gunning Dory are designed firstly as rowboats, with moderate sailing performance. If you want a sail & oar boat rather than an oar & sail boat, there are more suitable designs within your size restriction than either of those.

[ShagRock]

Thanks Chad.

And the reason for the asymmetry in the original is . . . . ?

Gary

Symmetry confuses, asymmetry points the way...more so with "gunners" on the water!

[Thad]

Full low in the bow gives lift, tighter toward the sheer reduces windage. Finer low on the stern reduces drag, fuller above adds lift when you need it, as when working between shortening rising seas around the shoal rocks where the gunners worked. This configuration is also marked in Chamberlain's Beachcomber where the hips at the stern will provide secondary stability and power as well as speed through lengthening waterline. In the double ender the breadth topsides in the stern can help pushing her back into the sea off a beach or rock as well as carrying a load.
Cryptic but maybe true, Shag.

[Gary Davis]

James,

Do you have some designs you would recommend I investigate?

Gary

[Gary Davis]

Thanks Thad - Gary

[kenjamin]

Gary,

Take a look at Welsford's Walkabout. It has a fairly powerful yet easily struck low aspect rig that doubles as the support for a neat camping tent which is also included in the plans – very clever! The Walkabout is still narrow enough to row fairly well and seems to be a good middle ground for a sail and oar boat. You can even row it with the tent in place if it's cold or raining or both. At 16' 2", I believe it will fit longitudinally in your garage. Also if you have a good marriage, you may be able to temporarily borrow a few inches from the rear wall cavity of your garage. (Cut open wall first, then ask for forgiveness).

http://www.jwboatdesigns.co.nz/plans/walkabout/index.htm

[James McMullen]

The Welsford Walkabout, the Oughtred Tirrik, the Vivier Ilur or Youkou Lili, Selway Fisher Islay Skiff, Swallow Boats Storm 15. . . .these are all glued lapstrake sail & oar boats that are more sailboat optimised, but still decent enough rowing boats.

If you could find a way to build outside or in a shed so that you could go up to 19' length overall, you wouldn't have to compromise and could just build a copy of the best sail & oar design in the whole world. :D

http://inlinethumb14.webshots.com/30029/2719202720088484686S600x600Q85.jpg (http://good-times.webshots.com/photo/2719202720088484686EwRxts)

[Gary Davis]

Beautiful Tern James.

If I did decide to shorten the 18' Chamberlain GD to 17', what must I do other than shorten the bottom by 6" fore and aft? I want to maintain maximum beam.

Thanks to all - Gary

[I, Rowboat]

The Welsford Walkabout, the Oughtred Tirrik, the Vivier Ilur or Youkou Lili, Selway Fisher Islay Skiff, Swallow Boats Storm 15. . . .these are all glued lapstrake sail & oar boats that are more sailboat optimised, but still decent enough rowing boats.

If you could find a way to build outside or in a shed so that you could go up to 19' length overall, you wouldn't have to compromise and could just build a copy of the best sail & oar design in the whole world. :D

http://inlinethumb14.webshots.com/30029/2719202720088484686S600x600Q85.jpg (http://good-times.webshots.com/photo/2719202720088484686EwRxts)

Hey James --
Great looking boat! Except you got the colors completely backwards. Contact Yeadon for some guidance on how it should be done.

[kenjamin]

http://ford.physics.fsu.edu/Xena6199.jpg

Try building a Caledonia Yawl in a twenty one foot garage!:D

http://ford.physics.fsu.edu/Boat6073.jpg

[John Bailey]

I think for your stated purpose you couldn't go wrong with Oughtred's Whilly Tern at 15'2"

http://i91.photobucket.com/albums/k301/JohnBailey_01/oughtreds-whilly-tern-caitlin-built.jpg


or Tirrik at 16'8".

http://i91.photobucket.com/albums/k301/JohnBailey_01/tirrik_rigged.jpg

John

[Gary Davis]

It looks like I can comfortably build a 17' boat in my garage. I think I'd really like the Chamberlain GD shortened to 17'. Oughtred's Amberjack plans should arrive soon, and I guess I'll have to make a decision.

To shorten the GD to 17', what must I do other than shorten the bottom by a foot and the planks accordingly? I found a nearby source for reclaimed vertical-grain, old-growth Douglas-fir with widths to 18". I plan to use other reclaimed wood from this yard for the stem and frames.

Thanks all - Gary