Need advice on ultralight boats

[pandelume]

I've been looking for a small boat that I can use at the numerous hand-launch locations in the Seattle area (I'd mostly be using those on Lake Washington's east side). Near as I can tell, these locations are mostly short stretches of beach in municipal parks and such. To use them I'd need something that can go atop my car - trailer parking is generally not available - and something I can easily carry single-handed from the parking lot to the beach. Basically, I'm looking for a small sailboat that can be used from kayak launches.

I've been looking at the geodesic airolite boats, and I like the concept. On the other hand, somehow none of them seem quite right for me. I suppose the closest would be the Westport Dinghy (http://gaboats.com/boats/westportdinghy8.html):

http://gaboats.com/graphics/westportdinghy_445.jpg

LOA: 8ft, beam: 43.5", midship depth: 14"
Unfortunately, she has no stock sailing rig.

Another that's caught my eye is the Selway-Fisher Redshank (http://www.selway-fisher.com/Otherupto10.htm#RE)

http://www.selway-fisher.com/Redsp3.jpg

LOA: 7.5ft, beam: 4ft, midship depth: 17.75"
At around 50lbs estimated weight, I could probably put this on my car and carry her over rocks without too much trouble, but I'm not sure.

I've recently developed a crush on Atkin's Handy-Andy (http://www.boat-links.com/Atkinco/Dinks/HandyAndy.html)

http://www.boat-links.com/Atkinco/Dinks/images/HandyAndy-1.gif

LOA: 8ft, beam: 4ft, midship depth: ~17.75"
At 90lbs estimated weight she's over the limit, but maybe she could be built lighter - perhaps even in geodesic airolite style. On the upside, I have a copy of her building plans from the Motor Boating's Ideal Series.

When you come down to it, I have a clear idea what I want to do, but I can't decide on the right boat - or even the right building method. I'd welcome any advice or suggestions.

[Thorne]

In some cases you may be better off with something longer than shorter -- easier to cartop load/unload, and not necessarily a lot less stable. Do the 'yaks really get carried all that way, or do some use small wheels?

Something more in the line of a sailing canoe or stretched ultralight might really work better. Thin ply can come close to equaling the lightness of SOF designs. Redmond's Whisp can be built quite light and rigged for sail as one Forumite has done.

Whisp -
http://farm2.static.flickr.com/1221/1346743111_ffea1c6b39.jpg
http://video.yahoo.com/watch/3302319/9289378

http://gaboats.com/graphics/cricket12_400.jpg
http://gaboats.com/boats/cricket12.html

http://www.storerboatplans.com/Beth/Beth8.jpg
http://www.storerboatplans.com/Beth/beth.html

[Hwyl]

As Thorne says, longer is often easier. I campaigned a Laser 13+ feet and 120 lbs. I carried on top of my Austin Mini Countryman, with a dolly on top.

I'd untie it, grab the back of the boat and slide it back about 10 feet, lay the back end on a lifejacket, walk to the car, grab the bow and swivel the front around and lower it. The the boat would be deck down on the ground.

You need a relatively low car and the ability to put the rear rack right at the back.

I admit, I was pushing the weight limit a bit with Mini, the set up looked like a mushroom. The glory of youth.

http://www.motorbase.com/uploads/2006/08/31/fs_austin_mini_estate_1966_rear.jpg

[Thorne]

Here is a shot from 2008 of Steve Chambers loading his Michalak Oarcle after the TSCA Wet Turkey Row on the Sacramento River. You can see the wheels mounted on the top of the transom, and picture how the length of the boat makes loading / unloading easy.
http://www.duckworksmagazine.com/09/splash/feb/index.htm#5

http://www.luckhardt.com/wt08-row9.jpg

Here's a similar rig clamped onto the transom of my Cosine Wherry -- which I trailer but can transport to non-ramp launching areas via this dolly setup -
http://www.luckhardt.com/cb-dolly1.jpg

[JimD]

It'll be hard to beat the geodesic aerolite designs if you want a short, wide dinghy. I agree with others that longer narrower boats will be much easier to manhandle on and off the cartop. But the aerolite boats are sooo light you shouldn't have any trouble. A 28 or 29 pound dinghy will be much, much easier to grab hold of and raise and lower over your head than a 60 or 70 or 90 pounder of the same size. I like the Black Fly pram
http://gaboats.com/graphics/BlackFlyFront.jpg

http://gaboats.com/graphics/BlackFlySide.jpg

http://gaboats.com/graphics/BlackFlyTop.jpg

[pandelume]

Thanks for the suggestions. I didn't think to mention it before, but I was intending to hang this boat from the ceiling of my garage - provided it's light enough. The problem with this is that there isn't all that much space that's clear of the opened garage door - around 8 ft, maybe 10 at a stretch. I wasn't thinking the boat had to be short to be light, I was just thinking of storage.

This isn't necessarily the most critical feature, but it would certainly make this project more attractive to Mrs. pandelume. I know it's bad form to leave information like this out; sorry about that.

[Hwyl]

You could akways start your own Frosty fleet, then the boat would fit inside your car, and it's 35 lbs

http://taft.com/BoatsBoating/Frostys/Frostys-11-29-09/images/_DSC4411.jpg

[Michael Beckman]

I'm currently considering a SOF pram of some sort to fit in the back of my truck.

I remember Zulu had a nice purple pram, perhaps Yeadon knows a little more about that design.

[JimD]

Thanks for the suggestions. I didn't think to mention it before, but I was intending to hang this boat from the ceiling of my garage - provided it's light enough. The problem with this is that there isn't all that much space that's clear of the opened garage door - around 8 ft, maybe 10 at a stretch. I wasn't thinking the boat had to be short to be light, I was just thinking of storage.

This isn't necessarily the most critical feature, but it would certainly make this project more attractive to Mrs. pandelume. I know it's bad form to leave information like this out; sorry about that.

If that's the case you might want to start by measuring exactly how much space you will have and go from there. However, its still true that when it comes to actually transporting the boat by yourself, beam and weight are likely to be the crux of the matter. Since dinghy's, especially yacht tenders, tend to be fat little load carriers you might start looking at row/sail designs, which could be narrower. Don't know if there are many that short, though.

The Weekend Dinghy from cmd.

http://www.cmdboats.com/images/wt.gif

http://www.cmdboats.com/wdk.htm?cart_id=a78c80ce3b80932c4fba94d828a59a62
Length: 9'-0"
Beam: 3'-4"
Draft: 0'-4" bd up
Weight: 70 lbs
Optional Sail: 37 sf Length: 9'-0"
Beam: 3'-4"
Draft: 0'-4" bd up
Weight: 70 lbs
Optional Sail: 37 sf

http://www.cmdboats.com/images/wdfull.jpg

[JimD]

Iain Oughtred's Auk and Puffin are very shapely plylap dinghys about 10 feet long.

[pandelume]

I measured the space last night, and based on that I'd say 8-9 ft length and about 4 ft beam would be about right. 10 ft length might be just possible, but maneuvering the boat up there would probably be tricky.

[pandelume]

Auk might be a contender:

http://i231.photobucket.com/albums/ee70/pandelume/auk.jpg?t=1262713996

I'm kind of conflicted - I really like all the non-SOF designs here, particularly the little stem dinghies, but I'm leaning toward SOF for weight.

[Cuyahoga Chuck]

The heaviest boat I can cartop single handed weighs 65 lb. It's an S&G pram that is 8' x 46". Because of the shortness I chose a pram to get a little more interior space. At 46" it is narrow enough to get in the bed of a mid-size pickup. Being plywood I don't have to have to be too particular about the waters I sail. Plywood may take gouges but it's not likely to hole.
Being fairly heavy and awkward to handle I can only carry it for very short distances. Anything more than 50 feet and I bring out my Wheel-eze canoe cart. Once on the cart I load it with all the necessary sailing equipment, put the oars under the sheet horse to form wheelbarrow handles and push the whole thing as far as necessary.
I made crossbars for my roofrack that were 62" across. That gave me enough room for the boat, the oars and the spars with enough excess for good purchase for the straps. The only problem I had was it cut into my gas mileage on long trips back when gas was over $3 a gallon.
Here's a picture of my initial cartop when my HHR was new.
http://gallery.bateau2.com/displayimage.php?album=lastup&cat=10905&pos=6
Unfortuneately I never took a picture of the wheelbarrow setup.

[G. Schollmeier]

http://www.boatdesign.net/gallery/data/3266/medium/P7250228.JPG
This was at last summers builders show I do not remember any details, may be Tim will. I have not seen one much smaller than this.

[JimD]

Can't say I've done it but if a dinghy balances roughly on the center thwart then cutting hand holds in could conceivably make it a lot easy to lift than trying to grab hold at the chine.

[obscured by clouds]

Blackfly

How about this for an elegant design

http://www.tdem.co.nz/boat/blackfly.htmlhttp://www.tdem.co.nz/boat/pics/blackfly/launch.jpg

at 8olb maybe a tad heavy, but the builder does'nt seem to be having much of a problem.

http://www.tdem.co.nz/boat/pics/blackfly/portage-2.jpg

the rest of this little site is a good resource too

http://home.clara.net/gmatkin/design.htm

[Hwyl]

Did you see this thread http://www.woodenboat.com/forum/showthread.php?t=86267

http://i174.photobucket.com/albums/w117/alias1719/HPIM3299.jpg

[Cuyahoga Chuck]

http://www.boatdesign.net/gallery/data/3266/medium/P7250228.JPG
This was at last summers builders show I do not remember any details, may be Tim will. I have not seen one much smaller than this.

It's not one of Platt Monfort's designs because there is no Kevlar roving. It looks more like Robert Morris's 8'9" Pram Dinghy. If it is the builder has fashioned his own sailboat modifications. None of that shows up in Morris's plans.

[pandelume]

Hwyl: No, I missed that one. I'll have to take a look at that Gardner pram in more detail when I get home. As I recall there's no stock sailing rig, but that could probably be sorted out.

I think a ~40lb limit on any particular part is about where I'll be comfortable - less is better, but if it's more than that I think I'll be dissuaded from throwing it on the car and going out for an hour or two, which is kind of the point. I like Auk, but I don't know if she could be built light enough - perhaps with 4mm planking?

Anyhow, you see my problem (or one of them) - I started out with a crush on Handy-Andy, and now I'm eyeballing Auk. Maybe what I really need is advice on how to make up my mind :).

[JimD]

...I think a ~40lb limit on any particular part is about where I'll be comfortable - less is better, but if it's more than that I think I'll be dissuaded from throwing it on the car and going out for an hour or two, which is kind of the point.

I think you are definitely on the right track with this thinking. Also I think you will have to go skin on frame unless you are willing to look at small canoes and rig them for sail.

[Steve Lansdowne]

That's me sailing my Whisp, reefed, in the first photo in Thorne's #2 post. The hull by itself is 75 lbs. with lots of spuce scantlings but also Dynel and epoxy on the bottom and bottom strake. I can load it on and off the truck rack solo, as I'm only lifting half that at a time, but to move the whole boat without a cart is too much for me (age 60 and not overly strong as compared with some folks). It is too wide to easily carry like a canoe is portaged, and with that size any wind that hits it the wrong way were I to try to carry it would lead to disaster (though I did manage to drop it onto a car fender once and the boat was not damaged, though the fender was, but that's another story). I always slide it off the rollers on the truck to a pad on the ground, with the bow still on the truck, then turn it over and later move it to a 2-wheeled cart I built to move it to the water. Larger and wider wheels go best over rocky beaches.

It does store up high in the garage and I can drive and walk under it, but barely. If you're talking a rocky beach for launching, I'd say not to. A skin-on-frame boat like Platt Monford designed would seem to me to be your best bet, though even then carrying a boat using only your body over a rocky shore with potential wind seems to be courting disaster. Cartopping anything much more than 50 lbs. on your own for loading/unloading gets old fast, though if you pay premium prices for the best / lightest wood (think Sitka spruce) your weight comes down.

[Hwyl]

Hwyl: No, I missed that one. I'll have to take a look at that Gardner pram in more detail when I get home. As I recall there's no stock sailing rig, but that could probably be sorted out.

I think a ~40lb limit on any particular part is about where I'll be comfortable - .

The nesting modification is Dave Gentry's, he's one of the nicest forumites and amenable to questions.

<putting my Thorne hat on>
You have not really specified what you want to do with this boat, once it's on the water, will you always be alone, or will you have passenger(s). Do you want to sail fast? Will you race or fish or picnic.

No comments on the Frostys .... anyone? Jim they're getting towards your perfect size.

[pandelume]

In a nutshell, my purpose is casual sailing on short notice. Mostly on my own, but occasionally with another person. Picnics also sound nice, if I can convince Mrs. pandelume to go for the occasional row ;). I have to confess that I'm not a very accomplished sailor, so something pretty easy to handle would be preferable. In other words, not really a performance machine, but fun.

The places I'm intending to sail from range from a few feet to maybe a hundred yards from from the parking lots, but the terrain isn't very difficult - I don't think beaching on rocks will be too much of an issue.

[dan-marques]

Another approach could be a boat you could disassemble, something like - http://www.clcboats.com/shop/boats/wooden-sailboat-kits/passagemaker/passagemaker-take-apart-dinghy-wooden-boat-kit.html

http://www.clcboats.com/scripts/phpThumb/phpThumb.php?src=/images/photos/boats/passagemaker/PMD-TA_grass.jpg&w=580

[pandelume]

No comments on the Frostys .... anyone? Jim they're getting towards your perfect size.

I browsed through the linked page and they look fun, but to tell the truth I don't know that I have enough experience for that kind of fun. Perhaps next build?

Dan-marques, have you much experience with the passagemaker? A take-apart boat with no part heavier than 40lbs might work well, although it might be a little heavy to hang from the ceiling.

[JimD]

Two part boats are easy to make if its a simple design http://www.glen-l.com/designs/sailboat/centerfold.html :

http://www.glen-l.com/designs/sailboat/sailboat-images/dsn-cfda1.jpg

[Dave Thibodeau]

Phil Bolger Design # 638 Queen Mab

length : 7'
Beam : 39"
Sail area : 35 sq ft
Weight: I built Just Ducky using 1/4 inch cedar strips which resulted in a hull weight of 28 pounds


http://web.comhem.se/chby/segling/QM04-A.htm


Dave Thibodeau
Concord Nh

[Martin Nelson]

I built a 12 geodesic airolite cqnoe for my dad several years ago. I didn't trust his abilities, so I added more floorboards and anther thwart. The design weight was 14 lbs and it came out at 16 lbs. He portaged it one mile into a lake with no problems. I also built several kayaks using the same technology. You could easily build a pram - skin on frame. I don't think you need the kevlar cross bracing. One caution is that the weight will be much less, so the boat may ride differently. I have used both dacron and nylon. Dacron is much easier to stretch and shrink tight. Pick a nice design and go for it.

[dan-marques]

No experience at all. Just though you could carry a whole very small boat, or half of a larger one.




Dan-marques, have you much experience with the passagemaker? A take-apart boat with no part heavier than 40lbs might work well, although it might be a little heavy to hang from the ceiling.

[DGentry]

Take apart boats are simple to make, just as JimD says. And, one piece at a time, are easy to carry around. However, the not-inconsiderable time it takes to put one together (there's lots of fiddling about) and, later, to take it apart again kind of precludes "casual sailing on short notice."

FWIW, that Gardner pram I built comes apart and nests, which, I suspect, is why Hwyl mentioned it.
http://i174.photobucket.com/albums/w117/alias1719/HPIM3438.jpg

As many have already mentioned, SOF is a great way to go if you are looking for a lightweight boat. They are also cheap and fast to construct - I often build one in a couple of weeks.
Many a dinghy can be modified for SOF construction, and Monfort's "geodesic" Black Fly pram, already mentioned, has a sailing rig option - what else are you looking for?

If you'd rather have more boat, have you considered storing your boat on the wall of your garage, rather than from the ceiling? A couple of hooks and a length of rope are all it takes to stow my 18' wherry along the wall at eye level. The garage door doesn't interfere, at all, and it's very much out of the way.

That boat, 18' long, still weighs only 47lbs - one of the beauties of SOF! It's designed for rowing only, but, again, it would be pretty easy to modify many existing sailing skiff designs for SOF construction, if you want a much lighter boat. I'm working on one, myself (when the weather permits!).
Here's the wherry, RUTH.
http://i174.photobucket.com/albums/w117/alias1719/RUTH1.jpg

And, awww shucks - thanks, Hwyl!

Good luck!
Dave Gentry

[JimD]

How about a two part skin on frame?

[pandelume]

Thanks for all the suggestions. I'll make a virtue of convenience and see if I can adapt Handy-Andy for skin on frame, since I have the complete construction plans. Is the consensus that kevlar roving is necessary to prevent racking under sail, or would I be better off just beefing up the stringers and frames? DGentry, I see that Ruth has relatively few heavy frames compared to the geodesic boats (as does the SOF pram upthread) - I realize that she's rowing only, but would similar construction suit a sailing skiff?

I also like the idea of a lightly built Auk quite a bit, but I don't know very much about very light lapstrake plywood construction. I think I'll get a copy of Tom Hill's book and read up about it.

[wtarzia]

An outrigger sailing canoe made like a surfboard: glass and epoxy over foam, with wooden strengthening and abrasion-protection where needed. Sit on top design with a kayak-style seat. About 7 feet wide with outrigger, total beam (you could get away with 6 feet depending on your sail), about 16 feet long. Light, unsinkable, fast paddler, fast sailer, good conversation starter. --Wade

[Dave Wright]

An outrigger sailing canoe made like a surfboard: .... --Wade

Along the small outrigger lines I think this gentleman did an excellent job, and came up with more than a canoe. Maybe it could be done lighter???

http://www.lifebase.net/flaquita/


http://www.lifebase.net/flaquita/images/AlmostFlyingAHull_large.jpg

[paladin]

I think you could do well with a little effort....find a design you like...10-12 feet, make the molds, use 1/4 inch foal laced over the frames and sewn with a needle and thread, and heated with the missus hair dryer...if'n ya dunno got a missus, snith the girlfriends when she's not looking. Sand witha block of wood and 100 grit paper. Lay on a thin layer of kevlar cloth soaked in epoxy, followed by 3-4 layers of carbon fiber, followed by a layer of kevlar and maybe one or two of xynole fabric. Sand smooth....
turn it over and use a box knife to cut the threads and remove the mold......using thin strips of spruce, laminate the gunnels etc, then a layer or two of ash veneer....with care you should be able to build the entire boat, less sail rig and oars for approx 20-25 pounds.
You have a couple of choices...leave in the foam, or add another layer of kevlar on the inside for stiffness.

[DGentry]

Mr Paladin - glad to see you up and posting again. Hope you get to feeling better soon!

Your 20-25lb boat idea sound interesting, but I know little about building this way. Are you making an entire male mold with the foam, or just covering the forms? What's the hair dryer heat for?
And,
then a layer or two of ash veneer - is this to cover the whole outside of the hull (sounds like cold molding), or over the gunwales, etc?
Thanks - I'm just curious, as it's always cool to learn something new when it comes to boatbuilding!

Pandelum -
DGentry, I see that Ruth has relatively few heavy frames compared to the geodesic boats (as does the SOF pram upthread) - I realize that she's rowing only, but would similar construction suit a sailing skiff?

Yes, I do believe that this style of construction is is suitable for a sailing skiff, and I'm building one right now (though slowly this time, cause it's cold here!). You can beef up the construction wherever you perceive a need, and it will still be less complex and time consuming than the Monfort method. His style, obviously, is well proven, but uses many very lightweight bits, and lots of kevlar roving for stiffness.
Traditional SOF construction - another option - uses sturdier, but fewer, pieces, as evidenced by the SOF pram upthread, or even my own Wee Lassie.
I'm all about the self-promotion, so here's a pic!:
http://i174.photobucket.com/albums/w117/alias1719/WeeLassielaunched036.jpg

Good luck!
Dave Gentry

[OconeePirate]

Y'all now have me hung up on the idea of having a see through boat with a see through sail. Is that a heavy vinyl that you've got there? Searching other threads I saw reference to clear sails made of mylar? I could sail naked and subject everyone to every square inch of this beauty that God gave me, LOL.

[Canoez]

Dave - how has the vinyl's transparency been standing up to scratches and what-not?

[wtarzia]

Along the small outrigger lines I think this gentleman did an excellent job, and came up with more than a canoe. Maybe it could be done lighter???

http://www.lifebase.net/flaquita/...

--- That's good boat but I would not consider it ultra-light. In fact, my outrigger is very much like this one though Joe is a far better builder than I and no doubt made his lighter. I used 1/4 CDX plywood (just about the heaviest there is?) with 6 oz glass over outside, double layer on bottom, also inside up to water-line, and more stringers than I really needed. My seats are pine planks, so heavy. My crossbeams are solid fir, my ama is V-hull style like Flaquita, styrongly built and glassed. My boat is very heavy -- canoe hull ~160 pounds, ama/float 70 lbs, crossbeams total 30 pounds. You can shave a lot of weight off that just by using hollow crossbeams or aluminium, less glass-epoxy, and a glass over foam ama. But I do not think even that result will make an "ultralight" boat.

A well built wooden canoe hull to the proportions of Flaquita I suppose might be kept to 60 pounds, the cross beams ....I don't know; you do NOT want the crossbeams to break!.... say 20 pounds total with reasonable safety gfactor?, and the glass/foam ama maybe 30 pounds if you want it to bear your weight at least, then add boards and rig. I still don't call that quite ultra-light...? I am, not assuming any exotic materials like carbon; that changes the bet.

I built heavy because 1. I made and designed my boat (see it at wtarzia.com/outrigger) without any skills or plans, and people like me tend to build heavy until they learn something :-), also, built on a budget, but also 2. even a small outrigger can be fast, and I want the hull to more or less survive hitting something at my fastest speeds or 8-12 knots, as I am often in shallow water. I wanted a durable trailering boat I could land on rocks if need be, and that's what I got.

A guy I know built his 20 foot outrigger out of 1/8 inch door ply and glassed over, and resulted in a very light proa. -- Wade

[DGentry]

Yes, that's heavyweight vinyl. And lots of sails are made of mylar these days, in whole or in part - so . . . .

And, the transparent skin is doing well, so far. There are a few scratches at the bow, from sticking it into the mud along shore, but it's just fine otherwise. One just has to forego dragging it across the beach, up the bank or across the parking lot . . . and, at 17lbs, that's not a problem!

Dave Gentry

[pandelume]

I love the vinyl wee lassie. I see that the stringer and frame intersections are lashed, but did you use glue to join them together as well?

I've finished a preliminary model of Handy-Andy with 6 intermediate stringers and 12 bent frames. Here are the frame and stringer splines:

http://i231.photobucket.com/albums/ee70/pandelume/HA_SOF_Profile.jpg?t=1263416243

http://i231.photobucket.com/albums/ee70/pandelume/HA_SOF_Plan.jpg?t=1263416279

http://i231.photobucket.com/albums/ee70/pandelume/HA_SOF_Section.jpg?t=1263416297

And here with some solids:

http://i231.photobucket.com/albums/ee70/pandelume/HA_SOF_ISO_2.jpg?t=1263416344

http://i231.photobucket.com/albums/ee70/pandelume/HA_SOF_ISO_1.jpg?t=1263416373

There's one area I'm not very clear on - the join between the inner stem and the keel:

http://i231.photobucket.com/albums/ee70/pandelume/HA_SOF_Stem_1.jpg?t=1263416433

Would the stem be notched for the frames to run underneath or would the frames just not touch the lowest stringer and run over the stem? Similarly, would the transom be notched for the stringers, or would each stringer have a sort of cleat or knee joining it to the transom?

[DGentry]

That's some cool looking software - what is it?

Thanks about the WL. The ribs are just lashed to the stringers - though I did epoxy them to the gunwales and inwales. Lashing, screwing, nailing, gluing - these methods all have adherents (no pun intended).

Do get a copy, through interlibrary loan if need be, of Robert Morris' Building Skin-On-Frame Boats. This will have all the info you need about building dinghies in a traditional SOF manner - he walks you through two different styles.

I would say you could likely get away with both fewer ribs and stringers. Each one you add makes building a lot more tedious and time consuming. I, personally, always try to figure out the least I need to achieve the same shape.
Perhaps 4 stringers and 8-10 ribs could work - depending on your scantlings, of course.
Morris recommends lots of both though, so it's all just whatever you prefer. SOF is pretty open to interpretation.

Your first couple of ribs in that pic can easily skip the lowest stringer and just contact the stem. At the transom, you can notch or butt, it doesn't matter. Individual knees are an option, too, though I'd say they're a requirement for the gunwales and keel - along with a healthy breasthook up front.

For a couple of other takes on the SOF dinghy, check out these two links:
http://www.capefalconkayak.com/jwboat.html
http://www.capefalconkayak.com/adirondackguideboat.html

Looks good!
Dave Gentry

[pandelume]

Thanks for the suggestions. The software is catia v5. I'll vary the number of frames and stringers tonight or tomorrow and post a few pictures of the variations - I can see that having fewer intersections would cut the work fairly dramatically.

For scantlings I was thinking of .75" x .25in for stringers and frames, which would allow me to cut at least the stringers from standard one-by stock. Inwales and outwales 1.5" x .25" (two-by). Keel .75" x 1.5" (one-by-two), although I'm not sure about that, since I need a 7/8" slot for the daggerboard - perhaps additional .75" x .75" strips to widen the keel in that area? Stem and skeg would be .75" (one-by), and the outer stem/keel, which runs the entire length of the boat .75" x .25". Transom and daggerboard 5/8" ply. Maybe thwarts could be 5/8" as well, to use the same sheet.

[keyhavenpotterer]

Is it important to have convex hull shapes to keep the skin against the ribs? Would hollow mean the skin will not lie against the ribs?

The reason I ask is that here in the UK, our small boat magazine has included free plans for a 12' Paul Gartside double ended rowboat, and I think it might be suitable for building in SOF. There is some hollow in the stern though. What do you think?

http://www.gartsideboats.com/pgimages/12de-rowboat-126.jpg

http://www.gartsideboats.com/catrow.php#12de126

Brian

[DGentry]

Is it important to have convex hull shapes to keep the skin against the ribs? Would hollow mean the skin will not lie against the ribs?


A hollow does mean that the skin will not lie against the ribs, yes. But, this is not necessarily an issue. If the hollows are not great, water pressure will force the skin to conform the shape you have built into the hull. I've also permanently created shallow hollows in the skin with heat shrinking, with polyester skins, of course. {Much caution is needed when trying this, as burning through a freshly skinned boat would probably turn me - and most builders - into a raging, scrawny version of the Hulk for a bit.}

The Gartside boat looks just dandy for SOF conversion. The only potential issue I see is that there's a lot of bend in those gunwales - I suppose that's an issue no matter how you build it.

As for the hollows, just how much more turbulence will the hull generate with a bit less, if you build it that way? Perhaps nothing noticeable? Perhaps the lighter displacement will lower the WL, in any case. (I'm just rambling here, and I'm no NA . . . .).
I say go for it - it'll be cheap and quick, in any case, so you can't go wrong.

Pandelume, your scantlings sound mostly OK, in my experience (assuming you were asking), depending on what wood you intend to use. I'd recommend pretty stout gunwales and inwales, though, to help take the strains of sailing and rowing. RUTH's are 1.5x.75" (gunwales) and 1x.75" for the inwales (both are WRC), and there's still some flex when I pull hard on the oars. Using standard stock does make building a lot quicker - in WA I could often buy the exact right sizes and forego a lot of ripping and/or scarfing - very nice!

Dave Gentry

[keyhavenpotterer]

Paul's 20' Surf Dory design is classic surf shape using flat bottom section, and same shape at each end, with no hollows.

So a 12' handy surf boat in SOF using that style might be dandy.

http://www.gartsideboats.com/pgimages/154.jpg


Brian

[Woody Jones]

Do get a copy, through interlibrary loan if need be, of Robert Morris' Building Skin-On-Frame Boats.

Dave Gentry[/QUOTE]

That's a great idea. Didn't think of that! Got one headed this way through the library system.

Woody