Looking for a rowboat design

[HelmutSheina]

Just the 6 sheets of 6ply weigh 90 lbs at least, skin on frame as suggested would go close , the areas you intend to use the boat mean it will need airtight sections in case of swamping. The nesting suggestion halves the weight to the waters edge and is much closer to normal weight, rivetted or welded aluminium is also possible, good luck.

The only Port Sorell I'm aware of is on the Bass Strait coast of my home state of Bicrania; and thus this boat will be designed to handle a bit of rough.

 

[william stokes]

Greetings,
After spending some time with ChatGPT explaining the requirements needed it pushed out these specs. Of course it looks great on paper. I'm not qualified to determine if it's realistic.
Is this a reasonable spec for a rowboat design that could be built in ply/epoxy?
If so, is anyone so qualified interested in doing the design and build plans?
Thank you in advance.
Chris

1. Principal Dimensions & Performance Targets
Length Overall (LOA): 15' 11" (max from 16' ply)
Length Waterline (LWL): ~15' 2"
Beam Overall: 48" (1.22 m)
Beam at Waterline: 38–40"
Depth Midships: 16"
Freeboard (loaded): 9–11"
Draft (loaded @ 650–750 lb): 5.5–6.5"
Target Hull Weight: 75–90 lbs finished

Design Displacement:
• 650–750 lbs total

500 lbs people + gear
Primary Stability: Very high
Secondary Stability: High via flare
Seakeeping: Optimized for short-period Caribbean chop

2. Hull Form Description
Hull Type: Shallow-arch, soft-bilge rowing skiff / widened wherry hybrid

Sections:
• Soft U-shaped midship sections
• Slight V forward for wave entry
• Slightly flattened run aft for tracking + beach drag
• Flared topsides for secondary stability + spray control

Chines: Soft / radiused (not hard chine)
Rocker: Moderate fore & aft for maneuverability + surf handling

Bow:
• High flare
• Fine entry
• Reinforced stem for beach impact

Stern:
• Small reinforced transom
• Moderate rocker for following seas + landing

3. Structure & Materials
Bottom: 6mm marine ply
Sides: 6mm marine ply
Transom: 9mm marine ply
Frames: 9mm ply or laminated hardwood
Sheer Clamp: Laminated hardwood
Keel Batten: Hardwood or UHMW wear shoe

Fiberglass:
• Full exterior sheathing 6–10 oz cloth
• Extra glass on keel + bow + beach zones
• Heavy oarlock reinforcement pads

Finish:
• Epoxy sealed
• Durable marine paint (not bright varnish)

4. Frame Spacing & Structural Layout
Stations (approx):
• Frame spacing: 18–20"
• Total frames: 8–9 frames + transom + stem

Suggested Layout:
Station 0 — Transom
Station 1 — 20" forward
Station 2 — 40"
Station 3 — 60"
Station 4 — 80" (midship / rowing station)
Station 5 — 100"
Station 6 — 120"
Station 7 — 140"
Station 8 — 160" (stem)

Reinforced Areas:
• Rowing station bulkhead
• Oarlock frames
• Bow landing zone
• Stern grab/drag zone

5. Plywood Layout (Efficient Sheet Use)
Bottom Panels:
• (2) full 16' × 4' sheets scarfed or puzzle-jointed
• Split centerline bottom

Side Panels:
• (2) full 16' × 4' sheets each side (upper/lower if needed)

Frames/Transom:
• (2–3) additional 4' × 8' sheets

Total plywood estimate:
6–7 sheets marine ply per boat

6. Rowing Geometry
Seat Type: Fixed seat
Foot Brace: Adjustable
Oarlock Spread: 60–64"
Oar Length: 7'–8' recommended
Thwarts: Removable or fixed for rigidity

7. Rough Hydrostatic Estimates (Concept Level)
Based on similar hulls scaled:

Block Coefficient (Cb): ~0.42–0.46
Prismatic Coefficient (Cp): ~0.54–0.58
Midship Coefficient (Cm): ~0.85

Displacement @ 6" Draft: ~650–700 lbs
Waterplane Area: ~45–55 sq ft
Initial Stability (GMt): High

8. Beach Launch / Abuse Features
• UHMW or hardwood keel shoe
• Glassed bow stem pad
• Reinforced transom drag edge
• Internal handholds
• Non-skid floor paint
• Drain plug for rinsing

Try searching FRANCIS F KINNEY drew many when with a well know Yacht designer thin was S and S
WoodenBoat https://www.facebook.com/WoodenBoatPub/posts/my-little-dory-12-3-was-designed-by-francis-s-kinney-and-wasis-i-believe-describ/10154826077605603/

 

[flo-mo]

Selway-Fisher covers almost all areas of small wooden boat designs. My choice would be the Oarsome 15'2" rowing skiff, which meets most of the criteria listed. Rowing Skiffs https://www.selway-fisher.com/Rowskiffs.htm#OARSOME

 

[BlueBell]

A boat designed by ChatGPT.
Why not go straight to a rocket propelled spaceship?

 

[Wgrabow]

Building the Catalina Wherry | NOMAD BOATBUILDING https://nomadboatbuilding.com/building-the-catalina-wherry/

Edit: You might be able to find plans for something like this in one of the John Gardner boatbuilding books, they mention Gardner in the first video.

Beautiful boat! I like the design and the execution of this hull.

 

[Wgrabow]

For very high initial stability a dory type (flat bottom) is better. Any arch on the bottom will make it more tender.

And also make it harder to handle on a beach landing.

 

[Wgrabow]

A boat designed by ChatGPT.
Why not go straight to a rocket propelled spaceship?

I mean this respectfully, but you need to get with the program. Every day I meet people who are finding helpful uses for AI, improving their productivity. It does the 'grunt' work then real people add their creativity.

 

[BGW]

I am a bit of a fan of skin-on-frame boats and found this St Lawrence River skiff by Cape Falcon Kayaks particularly interesting in terms of this discussion

 

[CDBarry]

There is a book on ultralight boatbuilding which I forget the author of, but you can probably find it used.

Also look at what Chesapeake Light Craft has, at least for some ideas.

As to plans, I assume you are aware of WoodenBoat magazine.

Skin on frame is definitely worth looking at.

Make sure you comply with the Coast Guard rules for flotation and capacity. There is a boat builder's manual that can be downloaded free from the Boating Safety website.

 

[Horton HCCI]

The boat will be used for inshore rowing off the beaches of West Coast Puerto Rico. No cabin. Beach launch and recovery with every use. Coastal bays, light chop, nearshore surf zone conditions. Standard safety gear... PFDs, Small bailer, whistle, maybe a leash system? Probably carrying a small cooler. Priorities are stability, safety, durability, and no extra weight.
Feel free to email me direct at sandlinhouse@gmail.com.
Thank you

You could always look into a Bolger Nymph: duckworksmagazine.com/07/projects/nymph/index.htm. 2 sheets of 1/4 ply, around 70 lbs, seats two people as long as you're not going on an extended voyage. My dad built one as a yacht tender. Terrible for this purpose, as the aggressive rocker drags it down like no one's business when it's towed. But it's great for just bopping about in protected waters. He loves his. Pretty easy to build, as such things go.

 

[kerosene]

I mean this respectfully, but you need to get with the program. Every day I meet people who are finding helpful uses for AI, improving their productivity. It does the 'grunt' work then real people add their creativity.

sure I pay for Claude and used to pay for ChatGPT and Gemini (google). They are all totally hopeless in engineering style questions. And you have no idea at any point if there is something right in their answers or if they are utterly made up nonsense.

Just today I was trying to figure out (coincidence, boating related), what is the freeboard at the transom on coastal rowing single (as in coastal rulebook) and what kind of angle the rear deck typically has to drain out (they have typically open transom and sloping rear deck).

The short discussion included repeatedly explain rowing dynamics as if the person was sitting feet towards the bow. It also explained that the rear deck would slope so that it would be at its highest at the transom.
And in another discussion today I asked if homemade trailers are still possible in Finland and if I can weld the tow beam myself or if it needs to be officially approved an so on. AI: no need you can weld your own and easy to register. Reality: nope you can't, you need to apply for VIN and permit before hand and provide strength calcs and the bureaucratic fees add to the price of new simple trailer. AI gave made up nonsense mixed up with old rules from the way back. All very typical.

AI is handy for a lot of things - non critical summaries, helping with coding, translations etc. but it really does suck in engineering. People try to design loudspeakers with it - AI: "what a wonderful project, you can totally do it, just watch for these pitfalls: aaa, you need to make it like bbb and you just need to solder ccc and ddd and eee.

aaa, bbb, ccc, ddd, eee (and it being as easy) were all wrong. Otherwise great.

 

[kerosene]

There is a book on ultralight boatbuilding which I forget the author of, but you can probably find it used.

Thomas J Hill

Decent book. Lapstrake plywood construction. IIRC there are plans for one or a few, all smaller, boats.

There are many good plans around, making one's own without the legwork is not going to result in a good boat. And the cost of good plans will always be cheaper than in the reduced waste and mistakes, let alone if you value your time.
Having clear steps and most problems already solved by someone else is huge.

 

[CarlosK2]

"AI: "what a wonderful project, you can totally do it"

This

This is a worrying trend I've observed; more and more, artificial intelligences resort to flattery like a sycophantic advisor to a king: - You look so handsome today, "What an interesting project," "What a great idea you've had," and so on, mixed with a handful of old things taken from here and there.

 

[Horton HCCI]

This is a worrying trend I've observed; more and more, artificial intelligences resort to flattery like a sycophantic advisor to a king: - You look so handsome today, "What an interesting project," "What a great idea you've had," and so on, mixed with a handful of old things taken from here and there.

I agree that you definitely can't trust AI. I've been using Google Gemini to bounce ideas off of, and have caught it flatly contradicting itself from one exchange to another, and sometimes even in the same conversation, always with a voice of great authority and conviction.

I've found it's good for coming up with things to consider, though, if you then do your own research. And sometimes it's an even better and more frugal internet shopper than I am, which is saying something.