Keel material

[Steve Downs]

OK, here's the deal. I've been reading what a lot have had to say about keels, I even talked to Dave R1 about it but I'm still up in the air. Someone once said that if they had it to do over again they would build their keel out of plywood. I've been considering this seriously and would like to get a a few more opinions about plywood keels. Are they too fragile? What if I put an oak "shoe" on it. I'm ready to get started now, the workshop is done and I'm raring to go. I'm just hung up on this keel thing. Thanks in advance for any input.

[waynemunro]

I built mine out of ply, if I were to build another one then I would be a lot more patient looking for proper keel wood. At the time I was imapatient to get going and the ply looked like the perfect solution as it was there, and it was much cheaper. The economy of the ply was a little false however, as with a wooden keel I would have varnished and left it bright, with the ply keel I put kevlar on the bottom and then glassed over that. I think that the extra cost of that countered any initial cost saving.

that said however my keel was very easy to make, and was perfectly flat.. no trouble with any of the warping issues of the more conventional keels.

my weekender has shown no problems with its ply keel yet, though after only two 'voyages' that would not be expected (I don't expect any with time either, the keel is pretty well protected, and it spends most of its life dry on the trailer).

Wayne

[Zeroice]

I to have used plywood for the keel with success. It was easier to use and I feel that it is stronger because of staggering the joints of the layers farther apart than possible with solid wood. Ive had my boat in the water 3 times this year and it has no problems.

[Arnie Eaton]

I would NOT use plywood for a keel on any boat. I know it is nice to work with and much easier to stagger the joints, but has way too much open end grain. It's not hard at all to use plain sawn boards and stagger joints. I used both 12" wide boards and 6" boards for my Vacationer keel and it went together easy. I don't care how careful you are about covering the end grain water WILL get in. The keel is one of the most important parts of any boat but even more with these type boats. Just my opinion based on building small plywood boats for about 55 years.

[barnacle5]

go with the white oak or at least pressure treated yellow pine. when I was a kid on the farm we would cut our own trees with a natural crook and have them sawn 3 inches thick in flitch boards . dad and I built a horse drawn sled from them. that's what you used on a hillside farm for wagons will turn over or get away on a hill. anyway the oak runners would wear out the floor many times over and this was being pulled over rocks , gravel and what have you. a steel shoe will ease your mind when you're beaching her too. listen to Arnie. thanks, Bill

[Barry Pyeatt]

There have been many varied opinions about what wood is good for keel and if you can't find it easily then the alternative of plywood.

There are several "newly" launched Weekenders with plywood keels and several more that have indicated that their keels are plywood.

I would recommend that you go back and use the "Search" function and call up several of the discussions on wood choices and why they are recommended.

A good stair riser 2X12 can be planed down to suitable 1X12 stock and is available almost anywhere that there is construction lumber. Many Tool rental shops rent planers that will accomodate 12" stock. You end up with a lot of shavings, but hey, it is good mulch. Alsoiask about 1X12 fachia stock.

The biggest issues are cupping and warping. Go to the Glen-L.com site and read the parts about appropriate Wood selections for boat building. IN particular pay attention to selection of grain types. Vertical Grain, quarter sawn, plain or riff sawn. It doesn't have to be clear, just tight knots and as straight a grain as possible.

[Mark Gudschinsky]

I must agree with the white oak choice. I was raring to go and used pine because of availability. After having gone down the long path of construction I realised that it was a bit silly to get into a rush. I've ended up with a great boat but the one part that isn't rock solid is the one part that really can't be changed: the keel

[Dave R1]

Steve, can you get white oak? Or is even that going to be a problem as well? Like I said when we talked, I think you can deal with the open grain issue easy enough if you go with plywood. Still, I think plywood should be left as the final option.

I'd like to know how it works out for you no matter which way you go.

Dave

[Barnacle Jim]

Hi Steve,

Being inexperienced at boat building, I followed the Stevenson directions and built my keel out of pine. Now, though, I really wished I had used laminated oak or hickory.

I'm sure the pine will be OK, but I have much more confidence in hard wood rather than soft wood. Since the hard wood would have been a little heavier than pine, using it might have added a little more weight, and therefore, more ballast and stability.

[Steve Downs]

Thanks for your suggestions, it really helps. I tend to agree with Arnie. I cannot get white oak here in the west. I can get red oak and I know there's a difference especially when it comes to boat building. I'll probably end using douglas fir. I can get that locally. Maybe put an oak shoe on that although the places I'll be sailing have sandy beaches mostly.

Anyway, it sure helps to get a variety of opinions. Now I just have to start. I guess Peter Stevenson was right about first cut-itis. Thanks again.

[Jan Williamson]

Hi Steve,

So you have an "official boat shed" I'm jealous!!!

I used 6"CVG doug fir for my keel, planning to biscuit joint them. After much hesitation because of the cost at $6.00+/BF, I went ahead a bought it thinking of the warp issue. What I didn't anticipate was cupping. When I bought 4 of the boards home they cupped about 1/4". Our elevation is a dry 2400 ft, and the boards had come from a warehouse at a more humid 500ft. After a few days in my garage and a weather change the boards relaxed. Although they were not perfectly flat, I used many screws and clamps and got them together. As far as I can tell they are still flat, but if I were to to it again I would have used white oak, biscuit glued 4 inch boards and stagger the joints. At $2.85/ BF and I would have had the $200.+ for some other part. Got pics of your "boat shed"?

[JTam]

When I was looking for alternatives for building my rudder I came across this article http://www.mothboat.com/CMBA/Building/foils.htm

In it, they talk about how using plywood for rudders and centerboards is not a good idea because of "cyclic stress" failures. Pretty interesting reading.

"Some materials have a greater fatigue life than others. Ounce per ounce, wood is capable of operating at a much higher percentage of its ultimate stress level than most other .....However, plywood is not a good choice for cantilevered structures such as rudder blades and centerboards. This is because plywood is susceptible to rolling shear, shearing forces that roll the structural fibers across the grain.. Plywood's unidirectional wood fibers are laid in alternating layers, approximately half of them are oriented 90 degrees to the axis of the loads. Like a bundle of soda straws, which resist bending moments quite well one way, they simply lack cross-grain strength laterally and can roll against one another and fail under relatively low stress, especially in a cyclic environment. Therefore, when anticipated loads are primarily unidirectional, it is ideal to use a material with good unidirectional strength. Since only half of plywood's wood fiber is used to advantage, a plywood rudder blade or centerboard going from tack to tack (reverse axial loads) will fatigue much more rapidly than one built as described in this article."

[Steve Downs]

Well Jan, it's not exactly a boat shed. It's just a place to keep my tools dry and get them out of the garage. I'll still have to assemble the boat in the garage but at least I won't be tracking saw dust into the house. I'd like to post a picture but I need to get with Frank and have him tell me how I can do that. I've never done anything like that so he's going to have to walk me through it. Anyway, thanks for sharing your experience.

[Jan Williamson]

Steve, I was just kidding about the "boat shed" :wink: I just have visions of having a "boat shed", about 30 ft wide and 40 feet long. I think everyone on the forum would like the same. I would even call it a shop if that's what it took!!! But I have to use my garage and I am waiting to put on the bow sprit, because once it's on, the boat has to go outside. Or be very diagonal in the garage. I am able to get the garage heated to about 70 degrees with the two oil type radiant heaters I put out there. So for the rest of the winter I think I'll be able to stay busy. My boat is so ugly that I think if I posted a pic, it would discourage new builders :shock: I notice the beautiful perfect pics on this forum, and my boat just doesn't compare. I figure when it is painted maybe it will look better

[Frank Hagan]

Douglas fir is a traditional boat building wood ... the west coast's "white oak", so to speak. It should be available in Utah without any problem.

Red oak is a poor choice, as it has hollow spaces in it ... you can actually cut a 1/4" square a few inches long and blow air through it like a straw. Orientated the way the keel is made, you have a recipe for disaster as the red oak soaks up water and holds it in. Red oak can be and is used for salt water boats that are in the water all the time; kept in the water, the rot is kept to a minimum.

If you can't find douglas fir in 1 x 12, or laminate narrower 1 x's into 1 x 12s, you can get 2 x 12 stock. Look for #2 or better or, better yet, "select" construction lumber that can be planed down to 3/4" net. Select is a grade that is generally found in the west, and has only tight knots. If the lumber yard can let you select nice straight lumber, you might get lucky like I did ... I used green, construction grade 2 x 12s. If you do the glue up within a day or so of planing them down, they won['t cup, warp or twist.

Any knots or holes where knots fall out can be sealed and filled with epoxy.

[Joel]

I used 3 layers of 3/4" AB Marine fir plywood for my Keel. It is glued with Weldwood glue and screwed every 3" with silicon bronze screws. I thru bolted the bottom with 1/4-20 bronze rod at 7 points along the keel. I plan to have a large epoxy fillet at the keel / bottom joint. a white oak strip will be attached to the bottom edge after it is glassed with 6oz cloth and epoxy. All that said...... I have no idea if this will work!

Here's my theory. If I ever find the time to finish my Weekender it will be kept on a trailer. Based on my sailing schedule for the last 5 years I should find at most 10 days a year to go sailing. On each of those days the boat will be in the water about 8 hours. My point is: How you build you boat has a lot to do with your expectations. I think my boat will last at least 10 years under these conditions.

I did find some nice 1x12 CVG Doug Fir for $7/bd. ft. If I really wanted to do it "right" that would have been my first choice.

joel

[Tom Holder]

This just occured to me - if you use ply for the keel, you could laminate in a 1x6 of some good wood in the centre of the upper part of the keel. Sort of a fir biscuit in a shell of ply - no warping and a sturdy base to screw into. You would have to get a little fancy maybe with the curve of the keel but . . .

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=======| 1x6 of fir | <\\\\\\\\\\{| - sole of boat screws into here

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took three tries to make that lousy diagram :shock:

[Steve Downs]

Well, after burning up the phone for that past few days I finally found a great deal. I can get random width, 12' long, 4/4 white oak from a wholesaler in St. George for $3.28/Bd. Ft. and I' figuring I'll need around 78 board feet allowing for scrap. I'll go get it Monday and I have a friend who owns a cabinet shop who will let me mill it down to 3/4" thick so then I'll be on my way, to infinity and beyond! :shock:

[Frank Hagan]

Wow! Great price on the white oak. Might be worth a trip to St. George next time I get a project going!

[Johannah]

I just took a gander at Steve's profile which says that he's a draftsman in working life. 8) Wow, cool and useful. What a handy and relevant bunch of skills to bring to boatbuilding. I look forward to updates of your adventures in wood.