Cut steps for floors?

[Seth Wood]

I think I've read this somewhere but can't put my finger on the reference.

Does it make sense, or is it unnecessary, to cut flat areas in the backbone timbers so the floors can sit level?

It seems that the alternate is to bevel the bottoms of the floors to match the slope of the backbone, which I'm guessing will cause the floors to slide downhill when the floorbolt is tightened. That's no good.

If I do cut these flat areas, or "steps," is there a risk of rot forming in there? What's the generally accepted way of doing this?

Thanks for any help....

[Art Read]

Perhaps it depends on the construction, but I don't think I've ever seen the keel itself shaped to accept the floors, rather the opposite. I know I just beveled and notched each floor to land smoothly on the keel's surface, (as best I could...) and left the keel intact. Once the bolt holes were drilled through both timbers, "sliding downhill" wasn't really an issue. The bolts kept everything lined up. Hope that helps.

[ 12-16-2002, 05:01 PM: Message edited by: Art Read ]

[mmd]

I agree with Art - bevelling the floors is much easier than notching the keel. Also, no end grain is exposed to moisture this way, and a mistake is much less costly in a floor than in a keel.

[Art Read]

Good point... There's at least one erstwhile "floor timber" buried in my scrap bin as I write this...

[Seth Wood]

Okay, got it. Cut floors to match the backbone timbers.

But what about the very ends of the boat, where the backbone is pretty sharply angled? Surely there comes a point where it's better to notch the backbone, rather than have a floor with an acutely shaped foot.

For example, see Pardey's book, p.85 -- I don't have it in front of me but I jotted down that he trimmed a "step" in the backbone to take one of his bronze floors. This was in a fairly steep section of the backbone, near the stern if I remember.

I worry that as the backbone rises into the ends, the increasing angles that I'll have to cut the floors to, will compromise that floor-keel joint. Because the floor bolts will remain vertical, not necessarily perpendicular to the joint.

I can picture this but I may not be explaining it well. Any additional thoughts?

[Dave Fleming]

Seth, guestimation on my part but in Pardey's case it was much easier to notch the timber keel than try to trim the bronze floor. Metal vs. Wood, don'cha know.

[ 12-17-2002, 01:06 PM: Message edited by: Dave Fleming ]

[Seth Wood]

Yeah, but he coulda' cast the floors to the right angle. Which leads me to think that for him, in that spot, the angle was so steep that the floor bottom would have been as much next to the keel, as atop it.

I have a few spots like that too, and while I hate messing with those backbone timbers -- not to mention exposing end grain -- I can't think of any way to securely fasten the floors to these steep sections except by trimming the backbone to fit the floor. This design -- Buehler's 30' Emily -- has backbone timbers (stems, really) that approach vertical at the ends of the boat. And I've gotta get floors on them somehow....

[Pete Dorr]

Id be concerned that by cutting a big notch out of the keel would significantly decrease the strength of the keel. In the stem area the notch would be tall and the width of the frame which would likely be 1/3 through the keel. I think it would be better to put 2 bolts through the frame, the first vertical and the second horizontal.

[SailBoatDude]

I saw a large keel laminated with steps built in for the floors, on the West coast some years back. Rather then the laminate being over a form bread and butter, it was built up on it's profile, with the notches worked into the schedule. The keel looked like wood was being added to, not cut into. I could see a continuous line under the floor locations that would represent where a solid or laminated keel would be with the additional "ramps" to the floor landings worked in. The belly of this 50 plus footer had no ramps or notches (it doesn't feel right to call what I saw a notch) in the center third, but one for each floor towards the ends.

This looked to be a heavy displacement hull for a trawler or fishing boat, and probably not too light. It didn't look to add all that much extra to this keel, but if you're building a Buehler design "he" would have the reserve to carry the extra weight, for sure.

Maybe you could glue up a ramp or raised area for the floor to land with an angle you can better live with. Use one inch or less stock for this and good epoxy techiques.

You could also "split the difference" by cutting a shallow notch in the keel and a less dramatic slope on the floor.

[Seth Wood]

Okay, I took a close look at the plans last night and the backbone angles are not as steep as I thought. Shaping the floors to fit the angle will work fine.

Yes, I'd thought of splitting the difference between floor and backbone, though it seemed complicated. Perhaps the best way, as suggested by Pete D. above, is to add a horizontal bolt through floor and backbone, as needed for the very steepest sections. But I'm glad I don't have to do that.

Having not yet learned by doing, I have to learn by asking. Once again I am educated. Thanks to all who responded.