Jim Michalak's Boat Designs
118 E Randall, Lebanon, IL 62254
A page of boat designs and essays.
(1oct00) This issue will discuss the problem of motor and rudder sharing the same space. Next issue, 15oct00, will rerun the issue on emergency flotation.
A winter row with Piccup a long time ago.
MOTORS AND RUDDERS
When I started boating, around 1980, no production sailboats had built in mounts for outboard motors. Not even the larger boats like a Catalina 25. At least not that I remember. Instead they had aftermarket articulated mounts that were bolted to the stern. To raise the engine you would swing the entire engine and mount to the up position and lock it. I guess most production boats still use the add on mount. I think they work well, especially from the standpoint that when it swings up the motor usually comes well out of the water. These boats are actually designed as strict sailing boats with rudder on centerline. So the mount goes off to one side and usually looks pretty ugly although we've all gotten used to the looks. I think these mounts have got to be very good at snagging ropes and lines, although any outboard will excel at that.
By that time Phil Bolger had designs with flooding wells in the stern that allowed the motor to clamp to the transom like an ordinary motor boat, eliminating the need of articulated mount. His transoms still had the motor off to one side and the rudder on center.
As I recall MacGregor was the first production boat to use a transom mount (and Bolger's water ballast, too). I think Hunter has since copied both the transom motor mount and water ballast.
In the mid '80's Bolger also started a series of planing motor sailers which had the motor on centerline and a single rudder mounted off to one side. (MacGregor tried thr fast motor sailer too but but used twin rudders, one mounted on each side of the big centerline motor.)
And now on to our story...
A LITTLE WELL IN THE STERN...
Here is Karl James in Jewelbox a few years ago. This boat has a small well off to one side of the transom to the which the motor clamps. The rudder is on centerline.
There is always a battle to make the well large enough and still keep the stern deck intact. The other problem is that the rudder and tiller can interfere with the motor. On a birdwatcher type cabin like this the tiller has to run under the aft deck into the cabin, so it has to clear the entire built in motor well and not just the motor head. On a wide transom it is possible but on smaller boats it can get pretty crowded back there.
Here is something worth noting. If the motor, offset all the way to one side, doesn't swing up high, it will drag in the water on one tack even when raised if the boat is heeling a lot. The drag of an outboard prop dragging through the water is amazingly large and the boat will slow a lot. It will feel like you are pulling a sea anchor along. And maneuverablity is greatly reduced. You will be very surprised how much a lowered or dragging outboard will degrade sailing.
A BIG MOTOR WELL...
Karl's brother Pete saw Karl's Jewelbox and wanted a variation on it. Petesboat is overall larger at 24' vs 19' and Pete wanted it to be a planing motorsailer. That meant big power (to me). As a rough cut a planing boat needs a horse for each 50 pounds so a 2500 pound boat like the proposed Petesboat would need 50 hp to plane.
We felt the big motor would have to go on centerline. I thought the best way to go would be with a Bolger motor tray in the stern, a large well that, about 18" long fore and aft, that runs full width. There is no double bottom. The bottom of the boat is the bottom of the well and there are drain holes through it there so the well floods freely.
With the big motor on centerline, the rudder is offset to one side. We used only one rudder with the idea that if it didn't work we would have to go to the twin rudder system like MacGregor was using on its planing motor sailer. The birdwatcher cabin presented a complication for the offset rudder. To be effective in a knockdown a birdwatcher cabin must have all its openings on centerline. Otherwise the boat could flood in a knockdown. In a normal birdwatcher with rudder on centerline the tiller goes through a small hole through the center of the transom. But with Petesboat's wide well a similar tiller would require a wide slot to provide enough motion since the watertight bulkhead is 18" forward of the rudder mounting. What we did was use a linkage with a push/pull rod running from a control arm on the rudder stock through a small hole in the transom, then to a linkage to a tiller on centerline. So the skipper inside the boat only sees his big motor on centerline and his tiller on centerline too.
These Petesboat photos were taken before the big motor arrived (delayed by sticker shock) and you can see another advantage of the transom layout - you can mount several motors! Here is a photo of the boat with the small motors in use. You see the rudder mounted off to port.
These features all worked very well! Pete said the offset rudder (the boat also has an offset mast and a single leeboard) made no differnce and that when sailing it you totally forgot that anything was offset. A 60 hp motor eventually arrived and the boat sped along at 20 mph full throttle and planed happily at 15 mph at part throttle.
Petesboat is barn door wide and could have easily used an offset motor well like Jewelbox if it weren't for the large motor. But it worked so well that I thought that a smaller narrow boat might really benefit form a centerline motor and offset rudder. Here is how it looks on Frolic2:
Keeping the motor on centerline makes for better balance on a narrow boat and helps keep the lower unit out of the water when the boat is heeled. The tiller here has a short "hiking stick" to allow the skipper to handle the offset tiller on either tack but I'm thinking that a tiller that simply curves back to centerline might be better.
Again, the effect of the offset rudder was nil. Here is the boat sailing:
Here the boat has an electric trolling motor mounted on centerline. It all seems to work fine but as an aside, the builder reported effort getting the transom height correct. I drew it at a 15" height with a level waterline but I think the weight of the motor and operator (and battery in the case of the electric motor) depresses the stern such that the motor sits too low. Experiment a bit.
YET ANOTHER VARIATION...
When you look at all the different variations it looks as though in the real world it doesn't matter where either the rudder or motor go on the transom. Neither needs to be on centerline (except for a big motor, maybe). Why not give them equal billing and keep them out of the way of each other like this?
I suppose if the transom were 36" wide as it might be on a small boat, that the two items might have 18" between them. I've drawn a couple of boats like this but none have been built yet. Right now if I were building a sail/power boat for myself this is how I would do it.
I'll rerun an emergency buoyancy article..
PICCUP PRAM, SAIL/ROW PRAM, 11' X 4.5', 90 POUNDS EMPTY
Piccup Pram was the first boat of my design to get built, back in 1990, I think. I still have the prototype and use it regularly. I designed it to be the best sail/row boat I could put in the back of my short bed pick up truck. But I found it to be a good cartopper, too. It has capacity and abilities I had previously thought impossible in a 90 pound cartopper. The photo above shows the original 55 square foot sail on Pensacola bay a long time ago. Piccup is a taped seam multichine hull which can take a fair amount of rough water.
Piccup continues to be one of my most popular designs and I get nice photos from builders. Here is one of Richard Donovan hoping for more wind up in Massachusetts.
Richard's Piccup has the larger 70 square foot sail that I prefer myself. It's the same as the original but is 2' taller. This balanced lug sail sets on a 12' mast and rolls up easily for storage on its 9' yard and boom. The idea was to be able to store the rig easily in the boat during rowing and it works. There is a pivoting leeboard and kickup rudder on the boat and they can be left in place raised while rowing. Converting to full sail takes a couple of minutes as you step the short mast, clip on the halyard and tack lines, hoist the sail, lower the boards, and off you go. And the balanced lug sail reefs very well although reefing any small boat is best done on shore.
Here is a Piccup by Vince Mansolillo in Rhode Island, a nice father/son project. Piccup will be large enough to hold both of them. You can see the large open frameless cockpit, large enough for sleeping. And you see the buoyancy/storage boxes on the end.
But Piccup will take two adults as seen in the photo of Jim Hudson's boat. Jim's boat has a polytarp sail as does my own Piccup.
These boats have proven to be good for sail rig tinkerers (be sure to read and apply the Sail Area Math essay before starting). Here I am in Piccup with a polytarp sharpie sprit sail. The rig is different from the originals but the hull here is totally unchanged (except for paint) from the original shown on the beach at Pensacola.
I think my own Piccup has had about six rigs of different sorts and was always the test bed for the polytarp sail experiments. But, hey!, that's nothing compared to the tinkering Reed Smith did with his out in California. Here is his Piccup rigged as a sharpie sprit yawl!
Piccup Pram uses taped seam construction from five sheets of 1/4" plywood. Plans for Piccup are still $20.
Some of you may know that in addition to the one buck catalog which now contains 20 "done" boats, I offer another catalog of 20 unbuilt prototypes. The buck catalog has on its last page a list and brief description of the boats currently in the Catalog of Prototypes. That catalog also contains some articles that I wrote for Messing About In Boats and Boatbuilder magazines. The Catalog of Prototypes costs $3. The both together amount to 50 pages for $4, an offer you may have seen in Woodenboat ads. Payment must be in US funds. The banks here won't accept anything else. (I've got a little stash of foreign currency that I can admire but not spend.) I'm way too small for credit cards.
Here are the prototypes abuilding that I know of:
Caprice: A brave and experienced builder in Texas is making the 25' Caprice water ballasted sailboat. A big project.Here the builder plugs away at the aft deck.
Jon Jr has been completed by Joe Leinweber and Dan Ellis and tested to a certain degree. Click here to read about the test and the surprize ending! ("The waters are only safe until next time!")
Mayfly12: A Mayfly12 is now completed and has been sailed. Waiting for final photos but here is an initial photo.
AN INDEX OF PAST ISSUES
BACK ISSUES LISTED BY DATE
Mother of All Boat Links
Messing About In Boats
The Boatbuilding Community
Kilburn's Power Skiff
Bruce Builds Roar
Rich builds AF2
Herb builds AF3 (archived copy)
JB Builds Sportdory
Hullforms Download (archived copy)
Plyboats Demo Download (archived copy)
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