5.4m row recreational row boat

[mike1]

Hi all,
I'm trying to design an easy to build rowing boat for open water , and would like comments for the design to date.
requirements that I set myself are
easy to build ( sort of )
to take up to 2 rowers
open water but not ferocious seaways or storm conditions
good exercise so sliding seat is almost a must
I have settled on
5.4 m , multi chine, "double ender", construction light ply stitch and tape, covered with glass,the boat is not a true double ender the aft section is a bit finer than the forward, I hope to have enough bouyancy in the bow to lift it in small wave conditions length 5400 MM, beam 900 MM, depth amidships 325 mm, beam at 100mm draught 354 MM , displacement at 150MM free board 330 KG, I expect the weight of the hull to be in the region of 20 25 kg's, then to add weight of sliding gear and oars.
I attach some drawings
I look forward to comments.
Mike

[jelfiser]

at www.freeship.org you can look at various model for making compare and download a free sofware for making some basic calcoulation ...
i think you have to test transversal stability for your boat , may be making the hull a bit more flat should be more stable
also why don't you make a true scale model to see how does it work ?
good look
Francesco

[frosh]

It looks a pretty reasonable drawing for one rower, but explain why it is finer in the stern sections than the bow? You need to really decide whether one will row or two if you plan to use a sliding seat. If you are thinking two rowers I believe that it will need lengthening to around 6.5 to 7 metres for a really efficient easily driven hull for the greater all up weight. If it is going to be one or two, then I would think it will be very difficult to incorporate sliding seat(s). Have you checked the cost of buying pro built sliding seat units? It is fairly expensive.

[mike1]

Hi Jelfisher, thanks I know of free ship , but I'm not an engineer or Boat designer, I'm just drawing a shape that looks kinda pleasing to me. I dont even know what all the abreviations stand for .
What I do have is the center of Boyancy , displacement and a few others.
The bottom section, I've been guided by the whitehalls , John Gardner, a copy of the "Bailey whitehall" lying at mystic sea port, the St Lawrenec river skif, and many working row boats,, they all suggest that the dead rise should be at about 15 degree.
Frosh, This is not going to be a formula 1 version , but is essentialy a pleasure and exercise row boat. However ,I take your point about size , I guess I made the mistake of trying a one size fits all approach , thanks for bringing me back to earth, I guess that there should be two boats one for single and double fixed seat as well as single sliding , and one for doble fixed and double sliding. I'll change my approach now.
Regarding the runoff ,all the rowing boat books suggest that the entry should be fine and the run off even finer, The st Lawrenec river Skif is a good example of this ,, as are most of the surf skis in my town.Remeber that most of the double enders of old were working boats , and often were used in either direction.
As I've mentioned I'm not an expert , but am just copying what I've read , Kinda Monkey see Monkey do approach.
Yeah I guess the sliding seat will cost and arm and a leg , but maybe I can get away with something made locally in Cape Town South africa. Last time I wanted to import some oars the deleivery cost from england to CT was like buying a couple pf outbards. Will be making oars here , they want be as grand as the imports be will work quite OK.
Thanks for the imput
Mike
in Africa

[Tim B]

The idea of the fine bow being to reduce wave drag, and the fine run-out to reduce friction drag. It is perfectly sound physics.

You should take into account, of course, that the big problem in an open rowing boat is waves breaking over the bow or stern. I'd incorporate some sort of foredeck with a coaming to deflect water sideways at the aft edge of the fore-deck. You may also want some form of aft-deck for the same reason.

It looks nice.

Tim B.

[mike1]

Hi Tim, Thanks, . The reason for the bow being fine and the stern finer now makse sense.
i had'nt thought about waces and spray comming over the bow or transome.. now that you mention it ,, a Dory has a nice flair at the bow ,, the St Lawrence river skiff ( apparently an oustanding rough weather boat) has a fairly high proad bow. Both these attributes would make a drier boat in weather. The St lawrenece skiffs that I heard of also had a small deck in the bow and stern.
I guess that I shoul flair the topside near the bow and stern to give a nice shoae to deflect the odd wave ( not white water though).
and a small deck also makes sense.
I guess that I still need to work this up a bit before being adventurous.Kind regards
Thanks for the info
Mike
Still in africa

[nordvindcrew]

go with a stretched Gloucester Gull dory from Phil Bolger, they row well,are fast and can be rowed single or double. Plans for a sliding seat rig are available from Glen-L boat plans and look easy to build. I am working on wooden hollow shaft oars from an article in Wooden Boat several years ago. Lots of time, but light and inexpensive oars result

[nordvindcrew]

A practical reason to have bouyancy forward is to properly support the weight of the oarsman. Oar placement that is too far aft creates a boat that makes it hard to keep her head into the wind. A huge amount of energy is wasted trying to stay on course in a cross wind . "Front wheel drive" is more efficient by far. It's just another design compromise between ideal shape and functionality.