New here and need some info - Chincoteague scow frame spacing

[DE waterpirate]

I am a old guy with memories of helping my dad build many boats for gill netting and crabbing. I have just finished drawing a boat from memory and limited info on the net. The boat is referred to as a Chincoteague scow. Identified by it's spoon bow and a flat bottom. I am building a model now to check hull shape and such. My question currently is if planning for 1/2" ply for sides and bottom using ply on frame construction. Is there a rule of thumb for frame spacing? As drawn I am thinking frames 1x3 on 18" centers for a 16' length. The boats were known to be sturdy work horses of the back bays. finding a wooden example now is like finding a unicorn. The reproductions from the eighties in molded glass give lines inspiration, but little help with the wood framing details. any help greatly appreciated.

Thank you in advance
Eric

 

[DogCavalry]

My friend, you are looking for a book called Elements of Boat Strength by Dave Gerr. All will be revealed.

 

[Tops]

Welcome to the forum Eric.

There have been a couple/few recent threads from user 'Kiry Laufer' about a Spira panga build 18 feet long that is using 2x3 for the frames and floors.
Spira floor ribs https://www.boatdesign.net/threads/spira-floor-ribs.70906/post-986207

Otherwise the stock answer is to read Dave Gerr's Elements of Boat Strength as mentioned above.
I cannot say that I have read the book.

 

[HelmutSheina]

On Duckworks website you will find free plans for a garvey about that length by Weston Farmer. It will be a more agricultural solution than Doug Gerr's book will provide, but I doubt scantlings will be inadequate. Gerr gives education, Farmer gives fast access to answers, and plans close to meeting requirements. I did read he recommends 2 layers x ¼" marine ply for sides rather than 1 x ½".

Wanigan (Free plans)

The biggest collection of boat plans in the Universe

duckworks.com

 

[DE waterpirate]

Thank you all! Happy to be here. Will do a deeper dive here and look into the book. Will report back.
Eric

 

[philSweet]

https://collections.cbmm.org/Media%5C00001%5C1559-2003.0064.100632591001980000000.pdf

If built as described above, with a glassed file bottom, keel, keelson, modest chine and sheer logs, and side decks with a combing, you don't need a lot in the way of frames. The primary structure is longitudinal. There will be stringers inside for seat supports, or solid seat transoms, and a stringer for standing on outboard of the keelson. These can be gotten out of 1/2 ply. And either a rub rail or spray strake for reinforcing the topsides. The bow needs a stout crossmember - either a timber or a thick bow transom of two 1/2 ply joined. Aft of that, there needs to be a frame for the bitt. There would be a frame at the front of the cockpit area and another at the rear, and a ring frame glued to the transom. That's plenty on a 16'er. I'd use 5/4 or 6/4 boards for the frames, 4/4 for the transom ring frame. Optionally, you can put a floor grate in the bottom. That requires floors spaced for the grating slats. A White Oak 4x4 resawn to 3/8" thick boards works well. Gotten up into a grates, they need light floor frames about every foot. You might have a small forward grate near the bow and a bigger one in the forward half of the cockpit, with the aft part of the cockpit open and floorless where the deadrise is less than 5 degrees. At 16', you won't be able to bring the bottom all the way up like in the bigger one pictured in the article, so you will have a bow transom there. It should be canted back about 30 degrees. The one in the article is fully framed in mahogany, but it is a much bigger boat. I'd probably start using convention frames like that around 20'. For under 20', let plywood do what it is good at.

 

[DE waterpirate]

Thank you philsweet that is the exact article I derived my rough dimensions and general lines from. I answered a lot of my frame spacing questions through the " organic " method by reviewing a lot of plans. I am progressing with my model. question, why do the Garveys have the second transom shape in the bow? It is a $hit ton easier and simpler than pulling off the spoon shape, lol
Eric

 

[Tops]

There is a place on Facebook 'Scow Life' that has some photos.

How are you doing the design: paper and pencil, CAD, boat design software?

 

[HelmutSheina]

Eric could you maybe laminate the bow from layers of thin marine ply to get the shape you're after? Here BS1088 gaboon is available from 3mm (⅛").

 

[philSweet]

why do the Garveys have the second transom shape in the bow?

Because they don't need to roll barrels of rum out the front anymore. These old scows were the main line of rum running.

With better outboards and smaller boats, you need a flatter run over more of the bottom in order to run at higher speeds with varying loads. This led to a lot less tuck worked in further forwards, and less change in deadrise angle along the run. If you tried to put a 20 hp on that fiberglass boat, it would stand on it's tail and never flatten out. It works great at 3 hp though - cheap and bulletproof and able to carry a massive load compared to it's empty weight.

So what engine are you imagining and what loads are you trying to tote around. Two people and 800 pounds of crab traps aren't going anywhere fast no matter what you hang on the back, but 600 pounds of people and gear can do 15 knots quite easily in a 16'er.

 

[DE waterpirate]

Thanx for all the info and inspiration! I have not seen the face book pics, very informative. I am pen and paper with scaled drawing to design, then on to lofting after the model comes to life. I am not happy with my model based on the first drawing. Bow tapered in from the beam to much and the deadrise in the bow did not look quite right to my eye. I am going to draw again tomorrow and start another model. Yes, a lamination could be done to keep the spoon bow simpler. An adjustment to my design will prolly make it an obvious choice.

As for power, the old woodies I remember all had 25 Johnsons and got the job done just fine. I plan to follow suit. Tiller or stick steer to keep it clean and simple. Me, some rum, and a trot line or some traps and I will be happy.
Eric

 

[Tops]

Looking forward to see what you design/build. Here is a musing over coffee this morning, nothing intended for actual use...

 

[DE waterpirate]

So I joined face book.... To try and see if the talk of plans on the scow life group ever came to fruit. I have my doubts, but worth a try. In my deep dive on the interwebs I did find a design by Bedard Marine. The sponge docks 13,16,19. A close enough design to the Chincoteauge scow to pass in my book. It is stich and glue vs. ply on frame though.

Could I save myself a lot of time and misery by purchasing the plans and adopting them to ply on frame? Or am I simply trading one pain for another? Advice appreciated.
Eric
Quick search here answered that. One pain for another.

Tops,
We must have been typing at the same time. lol See above. Appreciate your musings!

 

[Tops]

You are welcome.

Most likely one pain for another. I had a similar pain happen recently: I bought a set of plans not understanding the build method and the cost roll-up on the material list and scuttled the build for the time being. The designer answered all of my other questions after the plan purchase...I should have not assumed and asked a couple before!

It would be interesting to see the Facebook plans surface and/or if Bedard or another designer could make a drawing more 'scow' and less 'skiff' in the bow and suited to your intended materials and methods. I did build a small stitch and glue that has its frames added after the plywood shape was developed. Going in that direction would be easier than trying to convert plans that rely on 'spiling' the plywood to match the frames or molds.

 

[philSweet]

Okay, so a plywood 16'er with modest power. Mine started out as a sailboat I built in the 80's. In 2008, my girlfriend wanted a skiff for herself, and we already owned or had access to about 8 boats. I wasn't about to get another one, so I converted the old sailboat into a 20hp skiff for pot-tending and general fishing. I Filled in the board slots, built a motor well, and hung a Yamaha 20 on it, and gave it to her.