Jim Michalak's Boat Designs
118 E Randall, Lebanon, IL 62254
A page of boat designs and essays.
(15July2011)This issue will sew up a new bimini for my AF4. The 1 August issue will talk about cartopping a boat.
THE BOOK IS OUT!
BOATBUILDING FOR BEGINNERS (AND BEYOND)is out now, written by me and edited by Garth Battista of Breakaway Books. You might find it at your bookstore. If not check it out at the....
ON LINE CATALOG OF MY PLANS...
...which 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.
Three cheers for Stan Roberts, too! He completed this year's very windy Texas200 in his new and thoroughly tested Family Skiff, with mizzen mounted. He carried all his gear and supplies with him for the week's event.
A NEW BIMINI FOR AF4
...Well, the old bimini sort of died. It had faded away and gotten holed over the years...
... and the storm at this year's Rend Lake meet gave it the final rip...
...So RIP, old bimini. It was made in a hurry ten years ago using a thin junk tarp that I found and it cost nothing.
A WORD ABOUT THE OLD BIMINI BOWS...
I think the bows of the cover are sort of the base of it all and can be the most difficult thing to come up with. In this case I had tried PVC pipes and found them too heavy and flexible so I say don't waste your time there. Rob Rhode-Szudy did a bimini article for Duckworksmagazine where he made his own bows out of steel tubes. Aluminum tube is ideal for a smaller bimini like this one, really large boats use stainless steel tubes. What I have here is another find, a set of bows salvaged from a pontoon boat that was caught in a bit of a fire. The fabric was apparently totaled, the bows bent, and some of the plastic fittings were partially melted but function. A great story! It was way too wide and long for AF4. To make it the right width I cut sections out of the middles of the cross tubes and then scarfed them back together with smaller tube inserts secured with small bolt. Then the height was reduced by shortening the sides of the bows. I never did get all of the kinks out of the tubes though and I think that still haunts it a bit.
I say this with the idea that at the beginning at least you might investigate buying an economy bimini which will come with aluminum bows and the required fittings. My AF4 bimini is 7' long and 6' wide and about 4' tall and a quick web check at overtons.com shows a new top sells for about $300, so keep that in mind. In spite of all the hype about top materials, I think they all last about the same, five to ten years with normal use.
Anyway, I think the bows should be tall enough so that you can stand under it without stooping, say 6.5' headroom in the middle. The cloth sides come down about 6" on the sides. You should be able to see the horizon without stooping I think.
One of the cool things about fitting these is that fitting can be done essentially remotely. That is you don't have to fit it while it is on the boat. Just measure the thing for the size you need and maybe mount your deck hardware to take the fittings. That is why there is no problem selling general purpose bimini tops for boats as overtons does.
BACK TO OUR STORY....
With that in mind I set up the old bimini by the barn with its guy ropes staked to tent pegs, pulling them taut and stretching the old bimini to shape...
When you do this eyeball it in every way to make sure it is not twisted. In particular I check to see that the tops of the bows are parallel with each other, and, as shown in the photo, the front bow legs are parallel and the back bow legs are parallel. In this case the center support bow is let down because the idea with the new bimini is that it will stretch straight from from to back with no hump in the middle. But the middle bow will be used eventually to support the middle of the bimini. (I need to mow the grass in the photo but it can wait.)
In the photo the old top is still there under the new blank I have cut from a piece of thicker white polytarp which I had on hand. The ripped section of the old tarp is hanging down on one end. The new piece is pinned right to the old top on the bows. If you just have bows and no old top you will have to mock it all up with ropes or straps to get the bows in proper position.
The new blank needs to be well oversided, about 6" longer than the original and maybe 10" wider. It should come down on the sides about 6". When you have it secured to the bows as desired, mark the curve of the ends, like this:
When you have the ends marked be sure to also mark the sides such that they will all be the same height from the bottom. Looking at the photo I should say I should have made the top tighter, with less sag, than I did. But I'm not sure this can be done with great precision at this stage, because...
THE GREAT BIMINI MYSTERY....
I think the thing about bimini fitting that gives one the fits is getting the fit correct. It is stretched between bows which are themselves usually fairly limber. You do your best to get the end curves exact but when you put it together later and yank on the guy ropes you pull the bows this way and that and they take on curves slightly different than your original set up. And then your top is tight in some places and loose in others. A quarter inch here or there makes difference. At least that is my excuse. More about this later.
...mark the sides with a straight line. That is where the side will end but there will be a hem along the edge so mark it again 3" past that first line and cut it there.
YOU'RE GONNA HAVE TO SEW...
...so get over that. Practice if you need to. Use polyester thread like the stuff Duckworks sells for light sail making. Here is my elaborate sewing arrangement...
The work is done on the shop floor with a low seat, an old ammo box here, and the old Riccar is atop a kitty litter pail. Use no substitutes.
Cut the sides allowing for the hem but leave the ends uncut for now. Sew in the side hems. I prefer to use the big zig zag stitch just as in sailmaking. In my case I rolled the hem material twice so in the end the hem band is 1-1/2" wide and a total of three layers thick there.
After the side hems are done, fold the top lengthwise down the center so it is doubled and note the markings you make for the ends. They may not match up well but the idea now is to cut the material now while it is exactly doubled so the piece will at least be symetric about the centerline. When you cut it cut about 1/2" past the line so you can hem it over to double its thickness there. Here is mine at that stage, sides sewn and ends cut...
After you have cut the ends sew in a bit of a hem to double the material there.
NEXT, MAKE THE SLEEVES FOR THE BOWS...
...The bows are attached with sleeves and a sleeve will start a lot of arguments. Some like 'em tight and some like 'em loose and some like 'em straight and some like 'em curved. Some won't live with a sewn on sleeve, they must be secured with long zippers so the top can be removed quickly. Alas, unless you have the funds and permission to get into places like Astrup that wholesales 10' long heavy duty zippers you are sort of stuck with sewing them on permanently. The usual factory biminis have sewn on bow sleeves in order to avoid the cost of the mega zippers. Well, I'm too cheap for mega zippers right now. There is another way. You could lace the bimini to the bows. You will need lots of grommets. One wonderful advantage to lacing is that it is sort of self adjusting. Hey, I'm too cheap for grommets even!
So, I'm a big sleeve guy. I see no advantage to a narrow bow sleeve. I made these so wide that they took up the entire curve and have a straight edge towards the middle of the top. Here are my sleeves cut for the initial stage of fitting...
The sleeves are layed out so that the back edge of the sleeve is about 4" past where the curve of the bow meets the straight side. Note that the top is really a flat piece of stuff now. The back edge of the sleeve runs straight across to the other side with an allowance for a hem. If you are rich and using zippers I suggest this sort of sleeve because you won't have to sew a curve into your zippers. Anyway, pin the pieces to the top so they won't shift and cut the sleeve to match the curve of the ends. The sleeves also need a hem on the ends to make them stout there. So first you unpin the sleeve from the top after marking and cutting, sew in the hems on the ends of the sleeves, then sew the long straight hems on the aft edges. Then pin it back on the top and sew the curved edge of the sleeve to the top. Be sure to run the machine back and forth several times at the ends of this sew line because it seems guaranteed that the failure mode will be for the sewing to rip out at the lower front edges of the sleeves. It looks like this...
Lay it all out flat and then pin that straight edge into position for final sewing of the sleeve. Use a pin about every 6" to keep it under good control. Like this...
Sew her down. If you were rich and had long zippers you would sew them here instead of using the single solid sewn seam as I did.
I haven't mentioned it yet but any center bows also need sleeves, but they are far simpler than the end sleeves. Just a straight 3' long and 4" wide sleeve for this case. You can omit the center bow sleeve and instead use straps to the fore and aft bows to control its position. This is actually a better way to locate the bow except that the straps are a big bother to a bimini that will be unfolded/folded a lot as they seek out anything that they might tangle with.
...HOLY CRAP! IT'S DONE!
Well, of course it is never done but now you have to take your bows apart and slide the bows into their sleeves and reassemble. You rich guys with your fancy zippered sleeves need only zip it on. My first trial looked like this...
Not too bad. Could be worse. A bit wrinkled but you might be able to pull some of that out in final fitting on the real boat so don't get too carried away with tailoring yet. Next onto the boat...
Same wrinkles but there is still hope in that with the boat on a beach I could really scope it out and adjust with the guy straps. But I wouldn't do any tailoring yet.
Here is how I would tailor it. This one is tighter on the edges than in the center so it can be tightened up a bit in the center by taking a bit of material out of the center. Stand at one end (best done with the boat solidly beached) and pull out any extra material to tighten up a loose spot, like this...
Then pin out the extra material like this...
Then you can sew down the pin line to remove the extra and tailor the fit. But of course you need to remove the top from the bows to do that. My old buddy Harold would now be telling me that is where the expensive zippers come into play. And he would have told me to hollow out those front and back curves an inch in the first place, before I sewed it together because bows always deform that way under pressure. You know, that lacing idea looks better all the time.
I took AF4 out for a spin but there would be no final tweaking because this year there will be no beaches. Carlyle Lake is ten feet over its normal summer pool, all beaches are well flooded.
This photo shows the best we could do, parking the boat about a quarter mile "inland" from our normal cove "beach" and even here the water was nearly three feet deep. This is often a cultivated field. The water now goes right through those trees all the way to the main lake again. But the new bimini certainly did its job with no changes needed except for cosmetics.
MIKESBOAT, SAILBOAT, 17' X 5.5', 450 POUNDS EMPTY
Mikesboat is a big Piccup Pram. It is slightly narrower in proportion. The idea was to have something like Piccup that was large enough to take the family so she has two bench seats 8' long. It should be a good expedition solo boat with a boom tent fitted over the cockpit. Mikesboat has the Piccup layout with buoyancy/storage chambers fore and aft but now there is also enough room for a small motor well across the stern. As a rule something like this needs maybe 2hp to run at hull speed and even then there would be some extra. This shape of hull with multichines has proven good in rough water with fair speed.
Sail rig is the same 96 square foot sharpie sprit rig that I used on AF3 and a few other designs (actually it is the mainsail from a Bolger Jinni design I built 20 years ago). This is a change from the balanced lug rig that Piccup uses but Mike had good experiences with his Mayfly12 which used the sharpie rig and that is what he wanted. I would expect the sharpie sprit to be slightly better to windward than the lug but not by a lot and the sailmaker's talents might be the deciding factor here. There is no doubt that the sharpie sprit mast is perhaps 50% longer than a similar lug sail might need.
Mikesboat uses taped seam construction. Takes nine sheets of 3/8" plywood and three sheets of 1/2", compared to Piccup's fives sheets o 1/4". So you see that scaling up a boat makes for a lot more wood and weight.
I dunno if Mike ever built his boat but Bill Moffitt in Atlanta made one to run the Texas200. He is an experienced builder and sailor and made a thorough job of it in a big rush towards the end. Launching at the Texas200 was its first time in the water. His wife sewed the sails the day before he left for the cruise, and this was her first set of sails! The sail rig he wanted was a lug main with a sharpie mizzen. I drew those up for him and they are now included in the plan set. Here is his boat under sail:
Here is another photo of the boat beached beside Chuck Leinweber's mothership Caprice (which was designed originally for Bill Moffitt!) at the end of the cruise:
The cruise involved camping through several nights and Bill did something I have always thought about but had never seen. He pitched a standard tent in the large Mikesboat cockpit. A lot cheaper than a custom boat tent, for sure, but it takes a big cockpit to handle it. Mike also had some sort of center platform to fill the space between the long bench seats:
Well, three cheers for Bill and son Paul!!! As far as I know the 200 mile cruise went off without a hitch, the boat right on. But I suggest that most of us couldn't get away with going on a long cruise with an untested design.
And here is another Mikesboat, owned by David Chase...
Plans for Mikesboat, showing both sailrigs, are $45.
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.
I think David Hahn's Out West Picara is the winner of the Picara race. Shown here on its first sail except there was no wind. Hopefully more later. (Not sure if a polytarp sail is suitable for a boat this heavy.
Here is a Musicbox2 out West.
This is Ted Arkey's Jukebox2 down in Sydney. Shown with the "ketchooner" rig, featuring his own polytarp sails, that is shown on the plans. Should have a sailing report soon.
And the Vole in New York is Garth Battista's of www.breakawaybooks.com, printer of my book and Max's old outboard book and many other fine sports books. Beautiful job! Garth is using a small lug rig for sail, not the sharpie sprit sail shown on the plans, so I will continue to carry the design as a prototype boat. But he has used it extensively on his Bahamas trip towed behind his Cormorant. Sort of like having a compact car towed behind an RV.
And a Deansbox seen in Texas:
The prototype Twister gets a test sail with three grown men, a big dog and and big motor with its lower unit down. Hmmmmm.....
Jackie and Mike Monies of Sail Oklahoma have two Catboxes underway....
And the first D'arcy Bryn is ready for taping. You can follow the builder's progress at http://moffitt1.wordpress.com/ ....
AN INDEX OF PAST ISSUES
THE WAY BACK ISSUE ARCHIVES
1aug10,Texas200b, Family Skiff
15oct10,Sail Area Math, Jonsboat
1nov10,Sail Oklahoma a, Piccup
15nov10,Sail Oklahoma b, Caprice
1dec10,Taped Seams, Trilars
15dec10, Bulkhead Bevels, Raider
1jan11, Mast Tabernacles, OliveOyl
15jan11, Knockdown Recovery, DarcyBryn
1feb11, Knockdown Recovery 2, Caroline
15feb11, Windsurfer Mod, IMB
1mar11, Rowboat Setup, Paddleplank
15mar11, Rigging A Lugsail, Hapscut
1apr11, Displacement, Marksbark
15apr11, Sharpie Sprit Sails, Toon2
1may11, Small Boat Rudders, Blobster
15may11, Sail Sizing1, Mayfly16
1jun11, Sail Sizing2, Ladybug
15jun11, Rend Lake 2011, Toto
1jul11, Trailers, Wooboto
Mother of All Boat Links
The Boatbuilding Community
Kilburn's Power Skiff
Bruce Builds Roar
Rich builds AF2
JB Builds AF4
JB Builds Sportdory
Plyboats Demo Download
Brian builds Roar2
Herb builds AF3
Herb builds RB42
Barry Builds Toto
Table of Contents