Small sailboat Design - advice requested

Car topping is an area where a little innovative thinking can save a lot of Robaxicet.

I've car topped boats single handed that others thought hard - without any strain or trouble. For me, a key is making a little castored dolly that attaches to one end of the boat. Depends on the hull type.

This allows me to move the boat around holding up just one end. I then usually approach my van from the back and already have a carpet on the back edge of the roof. I put the uncastored end on the roof and then pick up the other end and slide it forward on the carpet until I can wiggle it on to the roof racks. Once it is on the racks, the whole thing slides forward easy, and I can get it in place for tie down. One person and it is far easier than having any help.

Woodenboat last year had a supplement called "Living with Small Boats" that showed some really neat single hand roof top systems. One loaded the boat from the side and cantilevered the whole thing on the roof on hinges.

Right now my boat is hanging from the roof of my garage over the little car (so the van gets full height on the other side). Release one cleat and the whole thing drops down on the roof rack and you can drive out.

The point of all this is to let you know that with a little thought and napkin engineering you aren't limited to a little tiny boat that you can bench press single handed.

--
Bill

 

Cartopper, maybe?

http://www.instantboats.com/cartopper.htm

or even the Teal:

http://www.instantboats.com/teal.htm

 

Bill: I read the WB article, lots of good ideas there. I had a 80 lb boat a couple of years back that I used to invert and run up my van’s windshield on a two-wheeled dolly; modern windshields are part of a vehicle’s structure so it took it easily. However, I mostly load my plastic kayaks from the side, due to the shape of the roof-rack on the current van. Double-enders can be tricky to control when loading. My home-built canoes can be loaded with one arm though. A boat with a transom would be far easier to load as it would stay put while I lean it against the van.

As you say, the trick is to lift only half the boat while the van holds up the rest. I did some “napkin engineering” engineering for the PDR and it might be so short I will end up supporting almost its entire weight at one point in the process. However, I can have a box on the ground to rest the transom on so it slopes at a more gentle angle, leaving more weight on the roof-rack.

I have several boats hanging from various parts of my garage but there’s no way I could get a van in there! Soon I’m going to need auxiliary storage (or buyers).

 

While somewhat stubborn, I can take advice. So instead of the Puddle Duck I am going with a small skiff, about the same weight stripped for car-topping, but much better performance and probably similar stability - the same bottom width (4'). Chine log construction, 6mm bottom, 4 mm sides/tanks decks, should come to about 60 lb hull, 90 lb ready to sail with rig, rudder board and seats. I will have 2 rigs, about 40 sq ft for learning and taking out the Missus, if I can thaw her feet out, difficult to capsize with that small a sail but bouyancy tanks and re-boarding provisions just in case. Maybe a 70 sq ft rig later for fun.

thanks to everyone!

Sharpii2, good luck with 'Motha Jugs'!

 

I wouldn't call you stubborn. Definitely careful and certainly not capricious.

Which design got the nod as your inspiration?

I built a boat last year (pictured below) that was mostly based on 4mm for sides & decks - and having done so I would consider using the 6mm for the side decks that may be used for seating. The 4mm is quite flexible and we ended up putting knee braces every 12 inches or so to make it rigid enough. If the tanks are to be sat on or weighted, keeping them curved would help strength.

Build it pretty and the wife will want to go out. Pretty is more important than most people understand. I'd also put some thought into the design of the crew's "quarters" - a wide comfortable thwart for seating and movement or a floor-level daggerboard trunk that doesn't intrude on seating can make all the difference in the world. Make sure none of the working rigging gets in the way of her ride and your ride will be more pleasant. Stern sheeting and avoiding a boom vang may be worthwhile.

Another good point is figuring out how you can keep the boat stable at the dock for "passenger" entry and exit. Very light boats work best if they can be stabilized when tied up to the dock with a rope OR rail that keep the boat from heeling. Wide side rails (or "wings") that can rest on top of the dock help.


I really think you'll enjoy a little bigger boat more. Others may not have followed your posts as carefully as I have in the past, and remembering your years of wisdom is a major reason why I think bigger is far better. I'm almost 50 and even my flexibility isn't what it used to be.

--
Bill

 

Bill: that's a nice boat, looks fast!

I did a concept design, starting off with the PDRacer's overall dimensions and refining it into a flat-bottomed skiff with similar lateral buoyancy and stability numbers and more longitudinal stability, then fed it through my design process that I use for canoes to make construction as easy as possible - "lazy" being just a euphemism for smart. I ended up with a concept that looked very like PAR's neat little 10 footer, so I may just go with PAR's design if it suits my building methods as I haven’t done the structural analysis for my design yet. However, your notes on the value of size are well taken and I might stretch my own design to 12 ft since it has a little more beam, depends on how the exact weight comes out; that would give at least 50% more heeling resistance.

As you noted, 4mm ply is flexible. In my design I planned to use side tanks which doubled as torque tubes, large enough so she could be righted virtually dry following a capsize. As an experiment I built a 7' x 8" x 7" ama using 3 mm ply a few years back, when it came time to junk it, two of us stood on it (425 lb) and jumped up and down with the ends raised up on bricks, it didn't even creak. In the end I had to take a saw to it: an axe just bounced off or just made small holes. A closed box is amazingly strong and rigid. With the mast and board

I can do pretty! My canoes get a lot of compliments and interest when I take one out on the water; it isn't difficult, 20% attention to joints, 20% reasonable finish and 60% balanced proportions. I use a lot of math in my designs, the 3D curves are splines that are derived from conics. I find if I allow the material to take a natural shape it’s impossible to build ugly.

You have some good thoughts on crew accommodations: I was going to put La Missus at the transom on a nice stylish wooden chair with a comfortable back, like the "girling" canoes of 100 years ago. She has a parasol, but I will forgo the wind-up gramophone and small guitar that were de rigeur back than!

I planned to arrange the controls so I can pilot from forrard to give her lots of leg room. I was planning a small and simple rig, no vang, rudder controlled through a cord led around the gunnels and back through a bow block (a common trick in excursion yachts way back when) and sprit set nice and high for zero head-banging. Something entirely different for me when alone of course!

Boat stability for entry and exit is an important point. I generally launch from a sloping beach so I can part the flat, wide transom on the sand during the all-aboard, get yersef comfortable phase, maybe a little ladder over the transom that will serve for re-boarding during solo adventures, and then I can hop in over the bow which will bring the stern out of the mud. The hydrostatic on my conceptual design work out well for that.

What did you mean by "floor-level daggerboard trunk"? as I thought the trunk had to reach above the waterline by definition.

Terry

 

Flooring grade styrofoam (eg Dow Floormate) makes good deck beams, won't absorb too much water especially if the beams are arranged well clear of the floor so water will never pool on them, and also gives you some reserve buoyancy if the worst happens.

Extra length confers an awful lot of stability, even without beam, and there's also something to be said for a boat that's narrow enough that its very easy to step into the centre... A boat where you are more or less forced to step in well out from the centreline feels a lot less stable than when were the layout enopcurages your first contact to be on the centreline.

The limiting factors for the case height tend to be structural - the leverage of the board on the structure (and the structure on the board!), and the waterline when swamped... In a reasonably sized light boat without too much of a load on board the static waterline is really very low in normal use... And if you have a snugly fitting daggerboard so water ingress is minimal I guess the case might not have to be above the waterline when the boat is swamped. So your buoyancy arrangements are a significant input to your case design!

 

Your thought process sounds great. I'd have to agree with your reasoning.

If you build a false floor/deck at/slightly above the waterline, leaving an air chamber underneath you can have the top of the daggerboard trunk be at floor level - that is what we did on my boat, and it leaves the deck wide open for accommodations as there is no need for side tanks. This is the basis for most dry capsize dinghies - righting the boat causes all the water to immediately drain out the open transom.

The openness of these designs is wonderful for people - the drawback is that poeple often feel they aren't sitting "in" the boat as much because the cockpit has less depth. In a boat with adequate freeboard this isn't an issue but a low freeboard boat can feel kind of exposed.

My single hand skiff (Falco Mk III design by Eric McNicholl) IS stupid fast. The day pictured it was blowing 5-8 knots of wind and it was easily outpacing a club coach boat (we used for pictures) with four people and a 30HP motor. The caveat with this boat is that it easily exceeds my ability to sail it well - I've got a lot of learning (and swimming) to do. I'm very happy with it, but am working towards solving the "family" boat need like you - I'm rebuilding an old Snipe for similar duties - wife, kid & family outings without drama and swimming.

I'll probably be going through your neighborhood a couple times this summer - my parents live on Lake Huron near Tobermory and we usually try to spend some time in Georgian Bay on the water. If I get it done, I'll have the Snipe sailing up the Georgian Bay side of the peninsula from Lion's Head to Tobermory during our holidays.

 

G4: thanks, I hadn't thought about swamped vs normal waterlines before; good point to bear in mind.

Bill: the dry capsize technique I mean is often used in the PDR - using side tanks large enough to lift and drain the hull as it floats on its side with a bouyant mast. The side tanks will also make dandy seats with back support if I make the the inwale fairly deep. As you noted, a raised floor cockpit reduces internal height and is less comfortable in a small boat.

Currently I am studying a couple of boat books: "build a simple dinghy" by Nicolson and Reynolds, has some thought provoking designs; New Plywood Boats by Firth Jones is very open about his errors which makes his boat educational by allowing me to learn from his mistakes as well as my own.

I have boat plans for a sailing canoe and Rushton's Wee Lassie, and several study plans for skiffs but I've only designed and built canoes so far. My method is ideal for a light skiff hull, and I want to have input into the design but still don't know enough. However I need to know more about mast step and centerboard trunk construction before proceeding so I will probably acquire one or two more detailed plans. I want to mock up the inside, of course, since that is key. Also it would be a good idea to add a temporary transom to my 10 ft canoe, weight it to 60 lb or so, then try loading it on the van to ensure I will be able to car-top the new boat.

I have more than enough 4 mm marine ply on hand and an untouched sheet of 6 mm (just bought a small job lot) plus Baltic Birch ply which might be good for the transom, so I'm good to go once I clean out the garage!

 

I’ll just review where I’m at for those who are interested. I have to admit that progress has been severely delayed by health issues, mostly related to my old fart syndrome, but I expect to start building in about a week. In the meantime I have worked on the detail design and construction method. Clearing the rubbish in the workshop that accumulated from a bathroom renovation is under way. Materials are 90% on hand; just need some clean pine, a little mahogany trim and a piece of spruce for the mast.

Objectives remain as per the first post, but negative comments on the PDRacer were taken to heart especially after watching a video in which one pecked alarmingly as it took wind pressure from aft, almost pitch-poling and coming to a virtual stop.

The advice for bigger boat was also noted but took second place to my wish for car topper this time. However, I recall the quote “Your next boat will be bigger than your last” attributed to W. Pirrie - designer of the Titanic. I’ve already got enough wood for it ...

I did a little skiff design of my own based on your helpful comments, but eventually I settled for Par’s little 10' boat, as I didn’t know about sizing scantling, daggerboard trunk construction, sail plans and other stuff. She will be called “Dace”, a small, slim active fish I used to angle for as a youngster in the UK; pretty but difficult to catch!

Those who know me understand that getting me to build anything “as designed” is like trying to herd cats! First thing I did when Par’s design package arrived was analyze the lines, to see how much I could simplify the building process, being somewhat lazy. I have made slight changes to suit my construction method. The only visible difference is a slight change to the sheer line in the plan view. *

I also started a parallel thread to solicit advice on buoyancy tanks. I will have side tanks from transom to the foredeck, at sheer level, which will also function as seats and side decks, providing structural stiffness in what is going to be a light boat. They’ll be air-filled but will have air bags near the stern for backup. I’ll have some foam under the foredeck as well. It’s going to take a lot to sink this little lady: perhaps I should call her “Molly Brown”.

She will have 3 mast step locations so I can gradually increase the sail size. To know yourself is an important step on the path to wisdom. The mast steps are all in the foredeck which is a compromise between two of Par’s accommodation layouts.

Her first sail will be small, a Bermudan spritsail of my own design using Par’s sail plan. I will make the sprit boom a double wishbone, similar to those used for sailing boards, but the sail will have 2 layers and the halves of the boom will separate, so I can open it out double-size rigger for downwind, conditions permitting: instant spinnaker! That sail will be made of tarp material as it’s just an experiment. Later I will step the mast. forward and have a proper sail made up, using Par’s larger plan.

So that’s were I’m at. I will post some pics as I progress. I hope to get her into the water for the Summer, if the arthritis and sciatica permit!

* p.s., main reason for the slight change to the sheerline plan was to make the sheer plank development easier to calculate & cut. It's now all straight lines.

 

I did some building of Dace during June but July so far has been a wash due to a variety of things. Don't you hate the way Life gets in the way of Boats? Anyway, I'm back at work. She got her bottom on yesterday and is feeling a lot better now she is decently covered up! She is about ready for flipping over so the real work can start.

Here's some pics: sorry I haven't been following up earlier but this lot gets me caught up. More to follow.

Construction notes: the sheer planks are 4 mm marine ply, the developments are straight sided. The inwales and chine logs were glued on with Titebond III while the sheer planks were flat; that made them a bit too stiff so I had to slit them at 3" intervals.

The cutting table is topped with insulating foam which makes it very easy for cutting out with a hand-held circular saw. The straight-sided developments make cutting a snap, using an 8' guide customized to my saw.

Joints at or below the waterline are made with epoxy, including the stem, transom to sheer joints and bottom.

In the last pic the bulkhead can be seen, with a centerpost to support the daggerboard trunk. I cracked a chine log: the repair is visible but it is inside the bouyancy tank so it will not be seen. a pair of knees can aslo be seen at the transom, but these are only to hold shape for construction so they are smaller than normal. The scuppers are inboard to clear the buoyancy tanks. Dang: I just remembered that I forgot to seal and paint the scuppers!

The bottom and transom are fastened by roundhead steel screws while the epoxy sets: these will be exchanged for countersunk brass ones in the finished boat.

The full-length 3/8" Baltic Birch ply keelson is bonded to the bottom which is 6 mm marine ply. The keelson is supported aft of the bulkhead by a temporary 2/4 spine (held by the clamp), and a permanent spine is used ahead of the bulkhead to provide support for the 3 planned mast steps.

A clunky mold of 2 x 4's can be seen but that is temporary. The transom top is flat but will be shaped to a curve later.

 

Terry:

Dace looks great! I too remember fishing for Dace as a kid - although some people referred to them as Creek Chub.

I'm building a boat for my son right now - the garage has been elevated from it's lowly duties of storing cars and off-season paraphernalia to the lofty role of boatshop. I've been blogging the process - given the humble nature of the project and it's non-foiling intent I questioned the value of posting things here. Here's a link to the blog - I'd appreciate your feedback. I've gone through a whole bunch of the same decisions and issues that you have - reaching some of the same and some different conclusions!

Cheers,

--
Bill Strosberg

 

A garage can be used for many purposes, the wost thing you can use it for is storing a car, especially in Ottawa. Lived there, done that, watched several cars reduced to heaps of rust. I wasn't a boater back then, but I concluded that cars last longer when they are left outside. I had a fire in my garage a couple of years ago and during the repairs it was brought up to current code. At the same time I crossed some palms with silver and had the doors, insulation and wiring improved. It's now a nice workshop, but if I open the overhead door it quickly gets infested with local kids who are fascinated by the boatbuilding process. This assures an adequate supply of future boatbuilders!

I enjoyed your bog; as you wrote we have a lot of things in common. I would like to start a blog but I need to find webspace: did your internet provider give you server space?

I know Lee Valley Tools well, we have a branch in Toronto - I thought I had died and gone to heaven! I use Titebond III only where I can assure a perfectly fitting joint, which is easy when the joint components are laying flat. I think if my boat were intended to stay in the water I would change to epoxy, and would certainly consider a saturation coat. I don't use a lot of Titebond III, my current tube is on its third boat - it goes a long way in zero-gap joints. Although I use epoxy on a minority of joints I use far more of it overall.

Interesting account about phoning from Odawa to Tronna about unbranded Tyvek for sails. I am going to try tarp, I have got some nice silver stuff and there is a source of white tarp on the net - they even supply finished sails. Rather than using double-sided tape as some do, I sew mine, an old sailor's skill picked up from an old sailor; my dad "sailed before the mast" way back when. Spritsails are easy to make as they can be sewn flat.

What are the dimensions for your boat's daggerboard? I assume there will be one eventually. Mine is 1-1/8" thick which seems a bit much although I can do it but I would have though for such a little boat 3/4" would be enough.

Your stringer on the cockpit floor, or chine log as some call them, is exactly what I do between the sheer planks and bottom, except I glue it to the sheers first instead of the bottom. For my 5-plank canoes I also glue logs to the bottom edges, mount the bottom on the stems, and plane the bottom and sheer edges to accept the garboards or bilg planks. It's virtually impossible to get this joint to fit perfectly, I usually end up with gaps up to about 0.02" so epoxy is needed anyway here. I am thinking of trying out the 5200 marine sealant together with screws on a future boat.

After this very simple flattie I would like to try something a bit more shapely, perhaps a 5-planker or even a round hull using my version of lapstrake mooted in the zipper-seam thread. But I will try it on a canoe first.

 

I will put my grain of salt, since ancient kayaker is talking of less than athletic wife.
I am myself, due to age and circonstances not anymore athletic, and my wife eather.
the only requirement she asked was to have an enclosed head. Since I want to built to the cheapest possible by not going wild in size, I opted for a non trailable super heavy very small boat.
I designed a very deep, ballasted inside at high ratio, with a headroom at 4'6", two berth and a enclosed head. The lenght on deck is 22'. To keep it cheap, old fashion jib headed rig.
The super weight allow me to "walk" the deck and my wife to feel safe. The engine, to keep it cheap is a 9.9 Hp outboard.
All that for a wife who wanted a private head, condition non negotiable, for her to came sailing.
I love my wife, I want to sail with her, so orderd, I designed the boat around the head! Building start in October. I hope she like it

 

blogspot.com gives you the space for free. Very easy and convenient.

3/4 at the widest. 7.625 inches length. 3 feet depth.

I'll have to read the other thread to catch up.

--
Bill