Looking for a rowboat design

[Christopher Sandlin]

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

 

[TANSL]

Welcome to the forum.
One important thing you should clarify is how you intend to use the boat. For example, on the open sea, on rivers, in protected estuaries. Do you need a cabin? Will you be beaching it frequently?. What special equipment do you need on board?. In short, small details like those.
If you'd like, please provide a more private method for communicating with you and exchanging information.

 

[Christopher Sandlin]

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

 

[Tops]

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.

 

[Christopher Sandlin]

Beautiful boat!
However no way I can handle a 200# boat safely by myself.

This design looks closer.
16' Port Sorell Rowing Skiff Plans https://duckworks.com/16-port-sorell-rowing-skiff-plans/

 

[gonzo]

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

 

[Tops]

Beautiful boat!
However no way I can handle a 200# boat safely by myself.

This design looks closer.
16' Port Sorell Rowing Skiff Plans https://duckworks.com/16-port-sorell-rowing-skiff-plans/

Christopher, that is also a nice boat.
The 95# weight listed for that Port Sorell does not seem realistic for (6) sheets of 6mm ply plus framing, fasteners, epoxy, and paint.

I just made a tender from 1.5 sheets of 6mm Meranti and pine framing, taped seams and glassed outside bottom that is 50# bare and 62# with oars and some pool noodles as a not-so-nautical looking fender system. Once painted it'll gain a few more pounds.

If you used 4mm Okoume (30% lighter than Meranti times .67 as thick) for the Port Sorell, then the 100-ish# number seems plausible.

I have a couple 13'9" Sunfish sailboats at home, 140# each when not waterlogged, that I move around with an inexpensive Vevor boat dolly. The loaded dolly goes onto a utility trailer and the trailer get towed to the beach. The dolly then delivers the boat to the water's edge and the reverse to retrieve and go home.

 

[bajansailor]

Would the Gloucester Light Dory be suitable for what you have in mind?
Gloucester Light Dory – 15′-6″ x 4′-0″ – H.H. Payson & Company https://www.instantboats.com/product/gloucester-light-dory-15-6-x-4-0/

I met some folk once who had a two part nesting version of one of these dories - the bow would sit inside the stern, and it only took up 8' of length upside down on the foredeck of their 36' sailing boat. She had provision for two pairs of oars rowing together, and with her two crew rowing she was very powerful, happily overtaking small conventional RHIBs with small outboard engines, even going up wind.

 

[Rumars]

How about you forget AI and tell us what you told it instead. Why? Because unlike it we have a better grasp of what you might need, and definitely of what's possible.
Important things to know: one or two rowers, or one rower with (occasional) passenger, expected total weight of cargo and people, open water rowing experience.
500lbs for you and a cooler needs explaining, either you're unusually large or your cooler is, because that's normally a touring load for a single, not a day cruise. And if you always have a partner then you don't worry about the boats own weight. Experience plays a role, while most boats have flotation chambers, there's a difference between a self bailing design and one of the open boats.

Examples of boats you can buy plans and/or kits:

Expedition Rower Expedition Rowboat https://angusrowboats.com/pages/expedition-rowboat
Oxford Wherry Expedition Rowboat https://angusrowboats.com/pages/expedition-rowboat
Expedition Wherry Expedition Wherry DIY Wooden Sliding Seat Rowing Craft Kit https://clcboats.com/products/expedition-wherry
Anapolis Wherry Tandem Annapolis Wherry Tandem DIY Wooden Sliding Seat Rowing Craft Kit https://clcboats.com/products/annapolis-wherry-tandem

 

[gonzo]

Christopher: to be able to give you relevant advice, can you tell us what is your skill level building boats? I have seen amateurs start a lapstrake project without previous experience and take several years to finish a mediocre boat.

 

[TANSL]

@gonzo, so far, Christopher hasn't said he's going to build the boat himself, nor has he asked for advice on how to do so. He's only asked if someone could design the boat and draw up the construction plans. Wouldn't it be more relevant to answer his question?.
To draw up the construction plans, the designer will undoubtedly try to find out what resources are available. But that's implicit in the second phase, and so far, the OP hasn't shown any concern about it.
My philosophy is that you first have to know what to do and then how to do it. Perhaps I'm wrong?

 

[rangebowdrie]

Atkin & Co. - Rowboats and Outboards https://atkin.mysticseaport.org/Oar/index.html

 

[HelmutSheina]

Skin on frame construction, light, strong, fast and cheap.

Row boats https://gaboats.com/collections/row-boat

Plans by Designer - Dave Gentry - Rowing - Duckworks https://duckworks.com/plans-by-designer/dave-gentry/rowing/

 

[Ike]

I would suggest, as others have, instead of designing a new boat, look for an existing design that closley fits your needs. There are many designs on line, and the plans are not very expensive. Home - Boat Builder Central https://boatbuildercentral.com/ has lots of plans for different types of boats, most built of plywood with stitch and glue construction.

 

[trip the light fandango]

Beautiful boat!
However no way I can handle a 200# boat safely by myself.

This design looks closer.
16' Port Sorell Rowing Skiff Plans https://duckworks.com/16-port-sorell-rowing-skiff-plans/

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.