Blackfly Dinghy design

[smithb9]

I'm currently finishing a S&G ply dinghy that I designed and built myself. Of course, building a wooden boat leads one to peruse the internet and the forums here in particular, which I'm sure has led some (most?) of you to build more boats.

I stumbled across pictures from the Pacific NW, the boat "Big Food" in particular looks amazing to me. It's pretty awesome that you can sail out of a city, and find secluded islands to explore and camp on not too far away (we don't really have much of that here in Boston, maybe in Maine perhaps?)

I found the Blackfly drawings online recently, and have been toying with the idea of shortening it up to 12' LOA, and possibly also converting it to a double ender. The curves are fairly easy, so I don't really see any issue in shortening it up by reducing the frame spacing and keeping the beam. I don't know that I definitely want to make it a double ender, but this idea has also crossed my mind as well.

My question here is if anyone sees any potential issues with the shortening that I am overlooking? my thinking is that this could be a pretty nice winter project if I decide to go forward with it. My reasoning for shortening the boat is general size restriction, and also to make it easier to car-top.

[Ron Williamson]

Black Fly by The Great Bruce Taylor?
Send him a Private Message.
You might coax him out of hiding.
R

[smithb9]

I will try that, thanks

[JimD]

Shortening it and turning it into a double ender? Sorry, but I think you need to find a different design.

[JimD]

Blackfly's lines:

[smithb9]

Shortening it and turning it into a double ender? Sorry, but I think you need to find a different design.

well, I guess technically it would end up being a different design in the end, inspired by Blackfly I suppose.

[JimD]

well, I guess technically it would end up being a different design in the end, inspired by Blackfly I suppose.

Yes, something like this 12 foot peapod by Arch Davis, perhaps

[Daniel Noyes]

well, I guess technically it would end up being a different design in the end, inspired by Blackfly I suppose.

It's called a St. Lawrence Skiff;
and has been around for 150+ yrs., Check out John Gardner "Building Classic Craft" book, available from library or our sponsor WB

[JimD]

St Laurence skiff built in 1908

[smithb9]

Nice boats, I particularly like that Davis Peapod, would like it even more if it had a few more strakes.

I suppose I should mention that I work in naval architecture (although its mostly large commercial steel stuff), so the design element is part of the fun for me.

[Tim Marchetti]

I just did a quick loft of what a 12 foot double ender would look like using the sections from above. YUCK! It would not be a pretty boat. The Davis Peapod seems perfect. I think our host featured a build on it not to long ago.

[smithb9]

hah, that does look pretty terrible. Perhaps the Davis Peapod after all...

ironically enough, WB #222 is on my desk with the peapod right there on the cover!

[JimD]

I just did a quick loft of what a 12 foot double ender would look like using the sections from above. YUCK! It would not be a pretty boat. The Davis Peapod seems perfect. I think our host featured a build on it not to long ago.

Yeah, you'd definitely have to take the fine ends out of it. Just shrinking it doesn't look like a solution.

[Tim Marchetti]

here it is with the lines faired

[smithb9]

hmm, doesn't look too bad there. I may try building a model to see what I am looking at.

[Tim Marchetti]

hmm, doesn't look too bad there. I may try building a model to see what I am looking at.

All the sections are different from the original. Station 7 and the stems are the same.
I'd still go with a proven design(the Davis peapod)

[Oldad]

For some reason we like to reinvent the wheel. I wonder how many boats get built exactly to plans

[JimD]

Starting to look like a canoe alright. Lots of small canoes around suitable for sailing http://www.selway-fisher.com/Opcan15.htm



A teeny interpretation of the Adirondack

[smithb9]

The canoes are nice, but too narrow for my wishes. If anything I'll probably go with the Peapod, or something similar to it of my own design.

basically this, haha:

For some reason we like to reinvent the wheel. I wonder how many boats get built exactly to plans

[JimD]

MEDWAY DOBLE 12'6"
	The Medway Doble was drawn up for Mr. John Lidstone who, having already built one of our Highlander dayboats, wanted a lightweight, car toppable craft of double ended shape suitable for river and estuary rowing and sailing. She has plenty of room for a family and can be used for both beach camping and fishing. Her small transom can take an outboard hung over and behind the rudder which has a tiller that comes up through a hole in the transom. This neat arrangement allows the tiller to be used without interference from the outboard. There are also fore and aft decks with space under for storage or buoyancy. The construction is based upon 4 1/2 sheets of 6mm (1/4’’) ply using the stitch and tape method from pre-shaped hull panels.As with all our drawings, full details are given for the sails and spars. Example left is by Alex Short.
Medway Doble 12'6" Particulars LOA 12'6" 3.81m Beam 4'6" 1.37m Hull Mid Depth 1'7 1/2" 0.5m Draft 7"/2'11" 0.18/0.89m Sail Area 77 sq.ft 7.16 sq.m Approx. Dry Weight 95lbs 43kg Hull Shape Multi-chine with 3 planks per side Construction Method Stitch and tape Major plywood requirements for hull 4 1/2 sheets of 6mm exterior or marine plywood Guidance Use 2-3 adults for rowing - 2 adults for sailing Drawing/Design Package 2 x A1 drawings + 6 x A4 instruction sheets

[Bruce Taylor]

Hi Brian...I got your PM.

As I mentioned in my short message, I have some doubts about adapting the design in this way. I think you might end up with something better if you design an entirely new double-ender (or, as some have suggested, adapt a design that's already a bit closer to what you have in mind).

Blackfly was an experiment with a fairly narrow design brief. The object was to make a quick and manoeuvrable sailboat could be portaged by one person and carry as much as a sixteen foot open canoe. To accomplish that, I put a lot of volume into the hull (hence the boxy midsection). Also, since I planned to sail it often, and row it only when absolutely necessary, I gave it a lot of rocker and a bit of a flat run. Below the waterline, it's a bit like a Sunfish, in some ways.

If you keep the 4' beam and those fat middle sections while removing the transom and shortening by two feet you end up with a very different sort of boat...a very pudgy, buoyant little thing! Having gone that far, I don't see much reason not to redesign the central and bow sections, too...maybe soften the bilge a bit. Of course, the sail plan will need to be reworked anyway, and you'll want to recalculate the location of mast step and daggerboard. You'd be wise to redraw the sheer. In the end, it's hard to see what you gain by starting with Blackfly.

I think a lightweight lap-ply cartoppable peapod is very good idea, by the way. If I were to do Blackfly again, I'd probably do something very similar to what you're suggesting. However, I think I'd start from scratch, rather than try to modify the old plans...

[JimD]

Doug Hylan's 13 foot Beach Pea might be worth a close look. 4'4" beam:





http://www.dhylanboats.com/

[johnw]

I'm unclear as to why you want it to be 12 ft. What's wrong with a longer boat?

[smithb9]

Hi Brian...I got your PM.

As I mentioned in my short message, I have some doubts about adapting the design in this way. I think you might end up with something better if you design an entirely new double-ender (or, as some have suggested, adapt a design that's already a bit closer to what you have in mind).

Blackfly was an experiment with a fairly narrow design brief. The object was to make a quick and manoeuvrable sailboat could be portaged by one person and carry as much as a sixteen foot open canoe. To accomplish that, I put a lot of volume into the hull (hence the boxy midsection). Also, since I planned to sail it often, and row it only when absolutely necessary, I gave it a lot of rocker and a bit of a flat run. Below the waterline, it's a bit like a Sunfish, in some ways.

If you keep the 4' beam and those fat middle sections while removing the transom and shortening by two feet you end up with a very different sort of boat...a very pudgy, buoyant little thing! Having gone that far, I don't see much reason not to redesign the central and bow sections, too...maybe soften the bilge a bit. Of course, the sail plan will need to be reworked anyway, and you'll want to recalculate the location of mast step and daggerboard. You'd be wise to redraw the sheer. In the end, it's hard to see what you gain by starting with Blackfly.

I think a lightweight lap-ply cartoppable peapod is very good idea, by the way. If I were to do Blackfly again, I'd probably do something very similar to what you're suggesting. However, I think I'd start from scratch, rather than try to modify the old plans...

thanks for the tips Bruce, I think I will try my hand at drawing something up. I like the look of the Davis Peapod, but wish it had more strakes (for aesthetics mostly), so something along the lines of that will probably be my direction.

[smithb9]

I'm unclear as to why you want it to be 12 ft. What's wrong with a longer boat?

its essentially an arbitrary length I picked, that will help me with regard to storage and portability. I live in the city and have a narrow alley to my backyard, and a "midget door" to my basement. I'm also just finishing a 10ft dinghy that takes up a considerable amount of space, so I don't want to go too much bigger (and 10 or 11ft seems small for a double ender).

[Thorne]

Given those limitations, why not design a SOF boat to meet 'em, giving yourself as much waterline length as possible? The design part would be very similar to working with marine ply, and the build and boat much more suited to your storage and transport specs.

[smithb9]

Given those limitations, why not design a SOF boat to meet 'em, giving yourself as much waterline length as possible? The design part would be very similar to working with marine ply, and the build and boat much more suited to your storage and transport specs.

I did briefly consider SOF, but its rocky in many areas around here, and I would be terrified of ripping a hole in the bottom.
Also, I think lapstrake looks very nice and fun to build

[smithb9]

did some fooling around in AutoCAD today, scaled the matinicus peapod lines down to 12' LOA. The turn gets a little narrower, but it seems like could work. The Davis peapod is very round compared to the matinicus, thinking the latter would be a better performer sailing.

[smithb9]

comparison of scaled Matinicus (left) to Davis peapod (right)

[Lewisboater]

The peapod would be the better rower... the other a better sailer. To sail the one on the right you would be on its ear most of the time because it has little stiffness to counter the power of the sails. It would roll like a barrel, which it resembles in your drawing. The left on the other hand has some muscle in the bilge turn and will stand up to a bit of sail. I wouldn't want to have over about 40 sf on it though...with the ability to put in a couple of reefs.

[Cuyahoga Chuck]

12'8" McInnis multichine bateau done in S&G
http://www.bateau.com/studyplans/MI1....htm?prod=MI12

[smithb9]

The peapod would be the better rower... the other a better sailer. To sail the one on the right you would be on its ear most of the time because it has little stiffness to counter the power of the sails. It would roll like a barrel, which it resembles in your drawing. The left on the other hand has some muscle in the bilge turn and will stand up to a bit of sail. I wouldn't want to have over about 40 sf on it though...with the ability to put in a couple of reefs.

that's along the lines of what I was thinking as well. Would be interesting to hear from someone who has build the peapod on how it sails, Davis specs 61sf for it.

[Lewisboater]

Must have a pretty heavy centerboard

[Dave Hadfield]

Bruce, how did the Blackfly end up? Did it function well for what you designed it for? Did you do any portaging trips with it?

What's it sail like?

Dave

[Bruce Taylor]

Bruce, how did the Blackfly end up? Did it function well for what you designed it for? Did you do any portaging trips with it?

What's it sail like?

Dave

Hi Dave. It's a good daysailer, but I'm sorry to say I've never used it for its intended purpose. Shortly after finishing Blackfly, I took up river tripping (I'm in the heart of Bill Mason country, after all!), and most of my camping has been on fast water with big groups of friends. I keep meaning to do a sail-camping excursion, and it keeps not happening...so, my "camping boat" has yet to go camping.