Jim Michalak's Boat Designs
118 E Randall, Lebanon, IL 62254
A page of boat designs and essays.
This issue will continue about knockdown recovery. The 1 november issue will continue the topic when we knockdown an IMB!
ON LINE CATALOG OF MY PLANS...
... can now be found at Duckworks Magazine. You order with a shopping cart set up and pay with credit cards or by Paypal. Then Duckworks sends me an email about the order and then I send the plans right from me to you. The prices there are $6 more than ordering directly from me by mail in order to pay Duckworks and credit charges. The on line catalog has more plans offered, about 65, than what I can put in my paper catalog and the descriptions can be more complete and can have color photos.
A bunch of pretty little boats by Bill Moffitt on the Gulf Coast, Piragua, Slam Dink, and Woobo.
In the last issue I presented an essay about knockdown recovery demonstrated by Herb McLeod with his AF3. This year Max Wawrzyniak completed an AF3 in St. Louis not far from here. One weekend we went out for a boat camp at Calylye Lake. On that Saturday there was no significant wind and we decided to take advantage of the calm conditions by doing a practice capsize of his AF3 (shown below with a classic 2hp Neptune mounted).
On reason I was looking forward to the test was to scope out the situation which Norm Wolf ran into with his Normsboat where the capsized boat floated nicely on its side and was easy to right but had its centerline slot pretty close to the water. Here is a photo of the situation.
Few knockdowns happen in calm conditions of course, and that open slot might look inviting to a large wave. When I made the first boat like this about ten years ago, a Bolger Jinni modified to have a small slot top cabin, I was careful to add segmented hard covers over the slot when sailing in rough conditions. I never capsized that boat and can't say how it would have done. But I feel the slot was covered sufficiently to minimize the effect of waves. I did similar designs like Pencilbox and AF2 and showed the plywood slot covers on the drawings but none of the builders built them. I'll admit that hardcovers are a pain. Eventually everyone moves towards soft covers and that is what Norm and Max use. I'm not sure how effective a fabric slot cover would be in keeping the waves out but I'm pretty sure it would be a lot better than nothing. Remember that the cover is not supposed to keep the water out for hours but just for a few minutes while the skipper swims around and rights the boat.
For any slot cover, the mast is something of a problem in that it is mounted on the side of the slot and would need to protrude through the cover if the cover were used while sailing. It was fairly easy to make a slot it my plywood slot covers. I think someone handy with a sewing machine could do the same with a soft cover but that is only speculation.
Here is what we did. The AF3 was beached and we removed the motor and all the loose things, although Max is much better at secure stowage than most of us. The boat was walked into waist deep water, parallel to the shore, and anchors run out from the bow and stern. The halyard was secured to the mast and its free end given to me close to the shore. So I could pull the boat over with the halyard while the anchors held the boat in place.
The sail was stowed to keep tangles to a minimum but the sail and boom can have an effect on the result. I would expect the boat would be slightly less stable due to the weight of the sail and boom up high. Once the boat is knocked down the boom and sail can help float the boat and keep the boat from going turtle. In fact that effect is really strong with a lug sail who's yard acts like a float out on the top of the mast. Then when it comes time to right the boat it is very very important to totally release the sheet because if water pools in the sail as you try to raise it off the water the weight of that water can make the boat much harder to right. (There can be other effects. Remember wind surfers? You never see them any more but 15 years ago they were all the rage. One day I was out sailing when a young woman fell off a windsurfer nearby. She climbed back on and raised the sail with the rope. "Did you see that!" she exclaimed. "What?" says I. "There were five fish in that sail when I pulled it up!" says she.} And don't forget that if you raise the boat upright with the sheet tight that boat might sail off without you!
Max sat in his boat in his usual sailing position while I tugged it over. He has a tilt angle indicator on his bulkhead although it maxes out at 40 degrees, I think.
I pulled it over and thought in a subjective way that the maximum righting force came at about 20 degrees which is what I expected. Almost any unballasted sharpie seems to behave like that. I continued to pull until the cockpit coaming was about to go under and flood the cockpit. Max said that was at about the limit of his gauge, 40 degrees. I was surprised that the boat still had substantial righting ability at that point unlike my old Jinni which capsized twice in tis career, both times it seems like way before any water came over the rail. But the AF3 was still hanging in there and you might be able to recover right up until then. Max had covers over his oarports which leaked slightly - a good indication that it is time to release the sheet although I can't imagine anyone seriously sailing one of these over 20 degrees of heel in a regular way.
Next I released the tension on the halyard so the boat rolled back upright. Warning! If you ever do a test like this give the skipper lots of warning because the boat rolls upright very quickly and the ride inside the boat can be rather violent!
Max checked things over and all was OK for the test to a full capsize. I tugged on the halyard and at about 45 degrees of heel the tension on the halyard was about zero. Over it came and I grabbed the mast when it approached horizontal and Max jumped out of the flooding cockpit. The righting moment continued in a negative way indicating the boat might turtle but when the mast tip hit the water it settled on its side like this:
Max righted the boat in an instant. He said there was nothing to it. Norm said there was nothing righting Normsboat and Herb said there was nothing to righting his AF3.
Once righted Max climbed back into the boat using the step hole he had cut into his rudder. It worked very well and I am going to show such a step hole in all future boats. The hole has no noticable effect on sailing.
Max bailed it out and that takes a while. There was no water in the cabin or stern locker but it was maybe 6" deep in the cockpit. In a real capsize this would be a critical time since the water in the flooded cockpit would roll around with each wave and make the boat a lot less stable. It is important to have a good bailing bucket handy and secured to the boat if you are sailing in capsize conditions.
When it was all squared away we capsized it again so I could get an idea of the effort needed to right it. Not much required. With Jinni it took my weight on the leeboard to right the boat but with AF3 I never got that far. When I waded around the stern I grabbed the chine and pushed on the bottom and up she came.
WHAT I THINK IT ALL MEANS....
I'm going to draw a narrower slot in future designs and go back to showing the plywood slot covers.
One question I have to ask myself is if a bit of added ballast will make these designs self righting. Not with the crew inside because that can be a very difficult situation to scope out in every way, but with the empty boat righting itself after the capsize and the crew is swimming. Then the boat self rights by itself before waves have a chance to flood into the slot. The crew doesn't need to swim except to get to the rudder toe slots and back into the boat. Then it is bail time. From what I have seen the amount of ballast needed might not be much, maybe less that 50 pounds. Maybe less if the weight is mounted on the tip of the leeboard. But you can't always plan on the leeboard being down and the tip ballast might make the board very hard to pull up. You can of course see a great danger in such a boat in that it might sail off without you very quickly so on second thought it isn't such a good idea. Then again, that situation is no different from the present where you must have the sheet loose and have a good grip on the boat when it pops upright.
But it would not be a major effort to find out. I might check it out using the Hullforms program but even better would be to wait until the warm water returns and Max gets bored with sailing on a calm day. Then we haul it over again and see how much weight is needed to make it right by itself. Luckily Max is a good sport.
We do it all again with an IMB.
ELECTRON, ELECTRIC CUDDY BOAT, 18' X 5', 900 POUNDS EMPTY
Electron was designed for a man who had done his homework on electric boats by reading Little's great book ELECTRIC BOATS. He wanted the ability to go about 30 miles on batteries. We started with my Fatcat2 design, stretched it to 18' and narrowed it to 5'. His figures showed he would need six trolling motor batteries to get the desired range while using a 24 volt 2 hp trolling motor at half throttle. The batteries will weigh over 400 pounds and the motor about 60 pounds. With wires and such the power system should go about 500 pounds which is why the empty weight of the boat is shown as a total of 900 pounds. To review the raw numbers, on hp is said to be 750 watts and should drive the boat about 4 mph. The batteries are 12 volts and 115 amp hours each, a total of 690 amp hours or 8280 watt hours. Batteries like these should not be drawn down below 70% of their capacity to prevent damage so the total power available is 5800 watt hours. So the system should run at 1hp for almost 8 hours, or over 30 miles in calm conditions. I should think that the wind will be the big unknown in the equation as it is in any boating. You start the design with 400 pounds of batteries in the belly and design around them. The batteries have to go in the middle of the boat for proper trim. The hull lines are kept sleek because we don't have power to burn, as we might with a gas engine. Multichines are used for light weight and good sea handling and speed. The belly needs to sink about 7" deep to give enough displacement to float the 500 pound power system, 500 pounds of people and the 400 pounds of empty hull weight.
The prototype Electron was built by Don Rodgers in California who instead uses a 2 hp four cycle Honda. (Must be aircooled - he said it was noisy.) I think Don said it goes 6mph at full 2hp. To me there is little point in using over about 4hp and that might be the preferred motor since you could run at half throttle at hull speed with some reserve left for tough wind and wave situations. A modern four cycle of tht power will run forever on a little bit of gas, and even a junker two cycle that size can go well on maybe a gallon of gas every three hours or so. A tiller extension is mandatory for proper trim, very easily done. (Don just told me the boat goes 12.2 mph with 10 hp and I'm surprised it was controlable beyond about 8.)
I also think this hull would be a good starting point for a sail boat. The lines are right. You would have to rethink the cockpit, trying to make it more watertight. There is a great temptation to use the batteries as ballast but I'm not so sure this boat is a good candidate for self-righting because its sides and cabin are low. And I suppose a boat with 400 pounds of lead in its belly should have six cubic feet of flotation foam so it doesn't sink if swamped or holed. There might be compromise where maybe two batteries are used, keeping the battery compartment small and yet with enough endurance for 8 or more miles in calm conditions. The weight of the two batteries might steady the boat but it might not be self righting. The drawings show a 114 square foot balanced lug sail, the same as the Bolger Windsprint, and leeboard but the sail rig is untried.
Electron is built from eight sheets of 3/8" and three sheets of 1/2" plywood using taped seams and jigless construction requiring no lofting.
Electron plans are $40.
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:
Sowsear: I'm told the Pennsylvania Sowsear is finished and has been tested. Should have photos soon.
An Australian buider has started a Dorado which is a power version of Frolic2.
AN INDEX OF PAST ISSUES
BACK ISSUES LISTED BY DATE
Mother of All Boat Links
The Boatbuilding Community
Kilburn's Power Skiff
Bruce Builds Roar
Rich builds AF2
JB Builds AF4
JB Builds Sportdory
Hullforms Download (archived copy)
Plyboats Demo Download (archived copy)
Brokeboats (archived copy)
Brian builds Roar2 (archived copy)
Herb builds AF3 (archived copy)
Herb builds RB42 (archived copy)
Barry Builds Toto
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