View Full Version : Challenging Design
12-30-2000, 11:47 AM
I have this odd wish to freight a boat out to northern Alberta, trailer it to Great Slave Lake in the Northwest Territories, launch it and cross that lake, cruise down the Mackenzie River to Great Bear River, go up the river to Great Bear Lake and cruise there for a month or so. (I told you this was odd.)
The boat would have to draw no more than a foot, trailer behind a half-ton, launch and rig without a crane, support 2 men for 6 weeks, contain a wood stove, survive many groundings on sand and gravel, be seaworthy enough to beat into 20knots and 5ft waves (or at least across them), sail (not just power, since there are very few places to buy gas), not cost the moon (since I might have to sell it up there), and, here's the kicker: make 12 knots with a 20hp motor to get up a swift section of the GB river.
Is this impossible? I had a scow design worked out til I found out about the 12 knot difficulty. Obviously I need a planing hull that sails not too badly.
Does anybody know of a sailing/power garvey or some such design that can satisfy a wish list like this?
12-30-2000, 11:59 AM
You don't ask for much, do you?
Bolger has plans that might amuse you but he generally likes lower power so you might have to have him modify a bit.
Actually sounds like - if you don't mind frozen snot, like a McGregor, perhaps with a beefed up bottom, would do you.
12-30-2000, 01:37 PM
You have some interesting requirements. I won't ask why you want to do this.
It may be that the best route to an answer for you is to get rid of the assumption that you have to have a planing hull to get 12kts. Long and narrow (high aspect ratio) hulls can easily make this speed without planing. The need for stability for sailing usually means a multihull in this category.
I don't know how fast a boat like an F24, or other similar trailerable trimaran would go with 20hp, but it should not be too hard to find out. This boat weighs only about 1500lbs and would launch off a trailer easily into shallow water. How you'd sell any boat that fills your needs in that country might be a problem, but maybe not.
Real honest to goodness 5ft waves are not a trifle to deal with for a small boat unless they are deep water waves of long period. How deep are these lakes?
12-30-2000, 10:39 PM
Ian, I was considering the M26x, but here in the Great White North it sells for about $20k (which is more than I care to spend) and it takes 50hp to make it plane. Also, the motor leg and prop hangs down too far. As for Bolfer, I guess I need to hit the library and go through his books. Most of his sharpies are heavily rockered though.
Tom, thanks. You know I hadn't thought of a multihull. It's worth exploring.
As for why, well, I don't thinks it's been done before. Reason enough. Concerning depth, it's both large and deep and cold -- many hundreds of feet.
12-31-2000, 09:36 AM
A multihull will prove quite a handfull trying to run a rocky river. That wide beam could realy hang you up. A sqare stern frieghter canoe should be your general model. They have been known to work in such conditions. It would be interesting to modify one to Bolger type construction methods. Say a folding schooner with a cabin added and the rocker left out of the aft hull and covered with kevlar and UHMD plastic sheet on the bottom. If you really need plans to build such a craft, you might not be up to the journey. Mistakes will be fatal, or will cost a lot of public money to get you out.
12-31-2000, 11:47 AM
Dale, you're right. I've done considerable northern travelling and I know that mistakes made on GB will indeed be fatal. I made the first transit by cruising sailboat of Lac Seul (a 125 mile-long lake north of Sioux Lookout), and cruised for 2 weeks along the north shore of Superior, as well as many other explorations, all in a M26. I really developed a taste for anchoring where No One Has Anchored Before.
As for the freighter canoe, that's interesting because it's what the indians use as they go back and forth from their camps on the Mackenzie. They put about 40hp on a 22-24 footer. I was thinking of staying on the boat though, rather than camping. Also they don't go exploring the lake for the heck of it, like I want to. They wait til winter and go by snow-machine. They don't have nearly the fuel to cover as much shore as I'd like to under sail.
Isn't the Light Schooner double-ended? I don't see how I could get it to go fast enough.
I'm leaning towards a garvey, but I had this idea of a bolt-on "sponson" under the aft part of the hull. This could be attached while the boat is careened on some beach, and would render the stern flat so that it would plane. Then, when in the open lake, it would be removed, and the bottom profile would return to its rockered, supposedly better-sailing shape. The sponson could also be built with a tunnel to protect the prop.
I'd use water ballast so that I could survive a knockdown under sail, but also lighten the boat for planing up the river.
I appreciate your input,
12-31-2000, 03:59 PM
I would not want to tackle a rocky whitewater river upstream with a wide beam trimaran either. Maybe it would be helpful to look into a boat that could be modified from the sailing mode to power mode for the different parts of the trip. Perhaps the sailing rig and a weighted keel or centerboard could be dropped off for the river part of the trip.
In Latin America, they have a fishing/work boat called a panga that is almost double ended. They have flat horizontal sponsons projecting under the waterline from the aft quarters to allow the use of some pretty big outboards. These boats are about 22ft long and are able to take care of themselves in waves as big as you mentioned. I've been whale watching on one and fished in their company in the Sea of Cortez. I have no idea how they would handle a sailing rig but the hull seems able.
If you are thinking about taking on some rough open water in a flat (or nearly so) bottom boat, you might want to study where this type of boat is used and where it is not.
12-31-2000, 04:57 PM
I'd be very surprised if any boat in this size range can be driven to 12-14 mph without at least semi-planing - consider that it will have a pretty good load - sounds like you could hit 1000# easy. The high-aspect ratio boats rely on being very light - if they're not, they automatically become displacement boats, with wave making, etc.
12-31-2000, 10:20 PM
Twelve knots is quite possible in a sharpie hull with enough power. Your add on apparatus will be to clunky to be worth much. Unfortunately compromise of speed under sail heavily laden will be necessary. Flattening the rocker will also compromise short turning on a long narrow hull. Two masts with an easily struck fully self tending battened rig with lazyjacks for the rig. An outboard with an attached jet drive mounted in a well would be just the ticket. I don't know if they are still being made though. Maybe a jetski powerplant if you could work some arc into the bottom ahead of the intake. Bolger's article on water ballasted craft in the last WB is required reading. Leeboards would be the only way to go. The little battery powered Hibatchi sold by Garret Wade would be a good place to start if engineering a lightweight efficent woodstove.
01-01-2001, 01:14 AM
We have either a misunderstanding or a disagreement. Many high aspect ratio hulls make speeds higher than the range under discussion in the displacement mode with no thought of planing. Few catamarans ever plane, even at high speed. The important factor seems to be aspect ratio and not displacement. Of course, lighter weight almost always means enhanced performance.
01-01-2001, 09:37 AM
Dave, sorry I'll be no help with the boat idea but reading your initial post made me think that either you have read or should read The Lonely Land by Sigurd Olson. I enjoyed it and it gave me the urge to go to Saskatchewan (which I've not done, yet). He led a group of five guys on a trip from Ile-a-la-Crosse near the headwaters of the Churchill River downstream 500 miles to Cumberland House. Sounds kind of similar to your trip. I hope you can make the trip and will write a good report of it. when you return, for us all to read.
For the woodstove and shelter, etc. I would be thinking about a John Atkin sea skiff type as getting close to your requirements, except for the $5000 limit. Or maybe Harry Bryans Handy Billy. Otherwise I would think a Grand Lake Canoe with the traditional camping set up would be the way to go if you need outboard power. I wonder about the usefulness of the boat for living aboard on the Northern rivers, but I would have to reread MacKensie or talk to the people I know who have canoed those waters to judge that.
BTY, have you read William Least Heat Moon's new book RIVER HORSE? [not to exactly recommend the boat, but the idea is good]
01-01-2001, 12:31 PM
A Dory or a Sharpie sounds like just the ticket. Glen L sells a motor sailing dory hull design called "Coaster", not the best looking, but real practical. An AS-29 by Bolger could tolerate a larger motor, as well as many several other Shapies (Norwalk Island Sharpies), their planning hulls should motor well. Sounds like a fun project,
best of luck.
BTW check the list of designs at Duckworks Magazine.
01-01-2001, 12:55 PM
Tom, a Panga? Interesting. I'll search for information. As for dropping things off, all I can do is portage items around the swift (on foot). At the upstream end I'll need it all again. When I enter the lake itself I could stash the sponson, if I built it that way.
As for weight, I know it'll be over 1000lbs stocked for a month, though I suppose I could portage the provisions, rig and everything moveable.
Dragontail? I've never seen one up close. This boat has to end up a sailboat. Ideally I'd like to keep the powerplant simple, though obviously a jet-drive would remove a lot of concern, weaving amongst the rocks. Leeboards for sure. Two of them, in case we break one. Also two masts, though the mizzen may just be a free-standing leg-o-mutton sprit. For the same reason.
Water ballast too. I'm familiar with it from the M26. It works, and it makes it easy to lighten the boat.
As for stoves, I make them. A simple sheet-metal non airtight 1 or 2 ring cookstove is an easy thing to make and wonderfully efficient, though I'll take a Coleman along as well. The lake only loses its ice in mid-July and never warms up, so the woodstove will have to warm the cabin and dry my clothes.
I have indeed read Sigurd Olson. Also Eric Morse, and the journals of many northern travellers stretching back to the Turrell brothers. Great writing. Informative too. That's why I don't want a canoe on GB lake. I want a cruising sailboat that draws so little that I can shelter in every tiny creek-mouth, and that can take a sudden blow-up on what is actually a very hostile lake.
Thanks a lot folks, for your ideas. Fair winds in the New Year.
01-02-2001, 09:54 AM
If you're thinking jet drive, check out the 'Tractor' (spelling approxomate, sourse easy to find in National Fisherman) which is a high volume low impellor speed unit. Very popular in the PacNW for sein boats and the like. They have one version that's every bit as fast as you need and the impellors are less prone to failure when you scoop up some bottom gravel, which is a huge problem for the high speed jet drives.
There's a US outfit making dragon tail type OB's - I think I found it cruising around in the motors section of John's. (Go-Devil.com) I think my gut's now large enough that if I just wear my jeans a little lower, learn how to talk coonass, and spit a bit more I could get one, go sneaking up the bayous looking for 'shine and 'gaiters, put a little shrimp in my hot sause . . .
[This message has been edited by Ian McColgin (edited 01-03-2001).]
01-02-2001, 10:53 AM
Maybe we are being too snooty about this. Take a look at this web site about a guy who is taking a Mac26 from the Artic ocean to the southern tip of South America. Can't tell how well he is doing.
01-02-2001, 11:35 AM
I've always felt that the whole McGregor phenomenon was like Phil Bolger bursting into plastic - funny looking things that on second look actually do what they say they will do and with a certain penache. Easy to laugh at until you see what their owners do.
01-02-2001, 01:29 PM
Tom - I'm not disputing the properties of high aspect ratio hulls. As I search in the tattered remnants of my education in naval architecture, I recall that there are two ways to avoid the energy costs of driving displacement hull to and beyond their hull speed (at which point, as we all know, bow and stern waves soak up most of the energy we're trying to drive the boat with).
One is by planing - essentially creating a form of lift by the dynamic interaction of the hull shape and water surface. All fast boats generate some amount of lift or planing force, whether they have classic flat run hull forms or not. It can't be avoided if you're going fast enough.
The other way is by adopting a very high aspect ratio hull, the classic example being a rowing shell. The very narrow entrance and run help to avoid generating waves, and the length helps maintain laminar flow along the hull. In light boats like rowing shells, this means there is little or no turbulent boundary layer, so drag is low.
My point is that achieving a high aspect hull form which also has large carrying capacity implies a rather large boat. 2 adults and 6 weeks of supplies led me to my guess of 1000# of load carrying capacity - although that may be a bit high. I'm not going to try to do numbers, but I can easily imagine that a classic high aspect boat to do this might be 30' long or more - sounds impractical for a river voyage.
[This message has been edited by Ross Faneuf (edited 01-02-2001).]
01-02-2001, 05:35 PM
Why not go with a historical craft? The most recent WB has an article on the Mackinaw boats, a version of which were used in the fur trade in much of your planned route.
The pictured boats are double ended - although I suppose you could make one with a square stern for an outboard.
Another idea is to modify a white water dory or driftboat for sailing, although dories do not make particularly good sailboats.
01-02-2001, 07:44 PM
I saw a Dragon-tail motor at Cabelas store. It had a 20 HP Honda motor. I forgot the price, but it seemed a lot cheaper than an outboard of the same HP. It is not in there curent catalog, but they may have information on there web site http://www.cabelas.com
01-02-2001, 09:20 PM
It is easy for me to get beyond my knowledge of hydrodynamics, especially when the discussion gets to Reynolds numbers and the like. There are many thoughts about on what does and does not constitute planing. Much of the confusion stems from a missunderstanding of the so called hull speed of a boat.
This is strictly an imperical formula for displacement boats of a particular range of beam-length ratio and no longer holds for most of the new crop of fast sailing boats. I observed one 21ft G-Force catamaran that AVERAGED 18kts over 67 miles from Wrightsville Beach to Atlantic Beach here in NC (officially timed during a race). A brief look at these long, narrow and deep hulls will make it clear that they could never plane on the water surface.
Whatever hull type Dave winds up with, one thing will have to be true. No hull with rocker in the aft part of the hull will be made to go 12kts under any reasonable amount of engine power. Anything resembling a traditional dory or sharpie will not work.
By the way, Ross, Charlie drove in today with the black locust. Really nice straight grained stuff. The black locust that I've had before was not nearly this nice. We will be able to supply cleat and knee stock for our community college boatbuilding class for a while. Thanks very much. We will make good use of it.
01-03-2001, 09:33 AM
You might like to talk w/ Barbara Burnside. Her old man, Paul Gartside, www.gartsideboats.com (http://www.gartsideboats.com) , and sometimes she, rowed down the Yukon to the sea thence to the Arctic. Haveing been there and done that, they may have words of wisdom to impart.
[This message has been edited by TomRobb (edited 01-03-2001).]
01-03-2001, 10:46 AM
Tom, I couldn't find out much about pangas, except that they look like rather standard sportfishing boats. I didn't see any arrangements to assist in planing. They look sturdy though. Do you know of any plans? BTW, I checked out the site of the fellow taking the M26x from the Arctic south. I can find no indication that he actually started. Did he? Did he ever get to "Chili"?
Ian, thanks for the Jet Drive tip. I like the idea. It's also a motor that's difficult to steal. Good luck with the gators. Be careful if it's them that prefer the hot sauce.
Regarding the planing hull vs. the multi hull, one thing to consider is that the "swift" in the river is shallow. The planing hull has the advantage of lofting me that much higher off the rocks.
Andy, I sailed alongside a "Mackinaw" boat in Penetang this summer. It goes well, for sure. The local Historical Society uses it as a sail trainer. I still don't see any way to get it up the swift though, and if it was square stern, it would be quite a different boat. Camping arrangements on board would be a little tight (on par with Shackleton's on the James Caird). I do though, plan to use traditional ideas. Chappelle's ASSC has some garvey plans I need to have a look at next.
I still don't see why I can't bolt on a false bottom for the aft 8ft (to get it to plane). I don't suppose it even has to be a hollow, watertight structure -- just a wedge to help the boat get up on the step.
Thanks to all,
01-03-2001, 04:01 PM
Here's a hairbrained scheme:
Build a plywood sharpy or dory - something like a 18'-20'power driftboat with a square stern and plenty of rocker and flare to the sides. Put a low cuddy on it. Triple up the bottom to put some weight and toughness down low. Laminate on 2x2 oak external chine logs. Next laminate on two 1x2 oak battens to make a 2x2 keel. Reinforce the stem. Now, prefab but do not attach a hollow keel. Frame it with 2x4s, sheath it with ply and have it run the length of the boat tapering from nothing at the bow to a depth of say one foot at the stern. Have its curve match the rocker on the bottom.
Next, pack it all onto a trailer with the hollow keel stored in the bottom of the boat. Motor accross the lake and then upstream to your sailing location. Beach the boat and fill all or some of the hollow keel with gravel. (You should experiment with the keel beforehand to determine where and how much gravel to ship for the proper center of mass, pitch etc, The hollow keel can contain several separate compartments separated by 2x4s.) Do not make the keel watertight as you want it to flood - not provide bouyancy. Attach the now weighted keel to the oak 2x2 keel batten with many deck screws through the ply sheathing into the oak batten. Unship the outboard and ship a rudder. Rig it and sail for a month or so.
When you're ready to leave, beach the boat, detach the keel, and dump the gravel. Unship the rudder and ship the outboard. Motor home.
The advantage of this wacky scheme is that you have ballast when and where you need it most but not when and where you don't need it at all. The gravel ballast is more effective than any water ballast could be because it puts the righting movement down low over the center where it does the most good. Also, you don't need to haul the ballast around on white water where it could cause problems.
My other whacky scheme was based loosely on the movie Chitty-Chitty-Bang-Bang - but I won't go there.
01-03-2001, 04:32 PM
Reminds me of a guy who years back approached me with a scheme to put a false keel that would fit on a catch devise on Goblin's centerboard to facilitate dropping the keel for product delivery . . .
But anyway, the idea of droppable ballast is an ancient and sometimes honorable idea.
01-04-2001, 10:23 AM
Here's a page about Phil Bolger's TENNESSEE
<BLOCKQUOTE>quote:</font><HR>I had always liked Phil Bolger's designs. He seems to get a nice balance between what makes a boat work well, what makes it look good, and what makes it easy to build. Tennessee is 29' long on a 6' beam and 4' high with about 4" draft, really just a big flat-bottomed canoe. She's much more than a canoe of course. She is a great little camp cruiser for two with lots of room for gear. She is not fast, but she handles a chop very well, and will float in very little water. At eleven or twelve hundred pounds, any old car will tow her<HR></BLOCKQUOTE>
BTW www.common-sense-designs.com (http://www.common-sense-designs.com) has folded, but there are other places that sell his designs.
01-04-2001, 04:48 PM
For Bolger plans, try http://www.instantboats.com
01-06-2001, 09:54 PM
I used the Plyboats program and drew up a garvey, a modification of a more rounded scow for this sailing trip. I couldn't remember how to post photos in here, but our new scanner allows us to post on the web, so here are 3 sketches. You have to enter the password, which is rhadfield . Then click on Log In, then Robin's First Circle, then Untitled Album. It's quite quick.
The boat is 25ft x 7ft 6in x 6in. It'll have a raised flush-deck cabin with a pop-top, leeboards, and water ballast. I drew it as a schooner to get the center of effort far enough aft. (I know it could have been a sloop, but I wanted 2 masts, because I like 2 masts, and I want them stayed.) The leeboards go at station 7, the widest part of the boat.
The question is, would it sail, in not too embarassing a fashion? I widened the stern and decreased the rocker quite a bit to make it look like it would plane.
[This message has been edited by Dave Hadfield (edited 01-06-2001).]
01-07-2001, 01:57 PM
Brian beat me to the punch line on sugesting the tennessee. I've a modifcation of it narrowed to 4 feet hinged in the midddle I'd make it at least two 24 foot hulls and fit it on a 8 foot wide flat bed. seperate cabins could have pop top ceilings to give standing headroom. and a chance for the two crew to spend time away from each other. the 12 to one length beam ratio should with 48 foot hulls has a natural hull speed of 9.2 knots but due to narrowness may give 15 knots with 4 to 6 horse power so tweenty should be plenty .
for sailing as much as I like Andys gravel keel ( which I think is great) but there was a design Mr Bolger did I belive for Mr Brad Story called the terantula ment to be a monohull day sailer but due to need for shallow draft was converted to a trimarane. I was thinking that for sailing you could carry a pair of floats and cross beams
best wishes on what I belive will be a great trip. also agree with the high volume low presure jet if it can hangle the gravel because the jet skis are rather sensitive to such.
Andy what was the chitty chitty bang bang idea?
01-08-2001, 02:08 PM
Last I heard about the guy with the Mac 26X who was trying to sail from Alaska to the tip of S America was that he had made it to the Caribbean and was running out of money. I believe he abandoned the trip shortly after that. That was a couple of years ago.
Depending on how it was loaded, I suspect you might be able to get a 26X up on a plane with quite a bit less than 50hp. You might have to blow out or pump out the ballast water, though, rather than expect it to drain out after the boat planed.
BTW, I like the comment that the MacGregors are a bit like Bolger in plastic. I made the same comment on another sailing forum and you should have heard the howling http://media4.hypernet.com/~dick/ubb/wink.gif
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