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Random Quote: You gotta be on the tracks when the train comes through
In making new stringers to help fortify my transom, i originally bonded the stringer directly to the hull with the intent of glassing it in. Then the realization of "hard spots" popped into my head. i cussed a bit and then created a 1/2 inch space between the stringer and the hull. i plan on glasing over that today. Just curious: did i just make a bunch more work for myself (that was a b!+(# to do) or was it worth to to keep any hard spots from developing on the hull? Thanks.
d
Glassing the stringer to the transom (bridging a gap) or having the stringer bonded to the transom then being glassed over; is that not the same thing? I would say so.
The glass when dried is very ridged and when formed in a channel shape and flanged out onto the transom; the transom has no where to go. So as I have said, one of the same.
Now given the two choices, I'd lean towards stringer bonded to the transom glassed over. But what do I know, JMHO.
Hey there Seabird. By hard spots i mean areas of extreme stress from boat flex due to not spreading out the load on a portion of the hull that is significantly stiffer than the surrounding region. For example, when bonding a backing plate for a new, below water thru hull, it is better to bevel the edges of the backing plate 45 degrees to help distribute the stress. By creating the space between the stringer and the hull, and then using differing widths of glass tape to bond the stringer to the hull, i could theoretically distribute the stress better. Maybe the key word is theoretcal. i am only on my 3rd cup of coffee this morning so i hope that i am making sense.
d
[This message was edited by Psycho D on 07-27-03 at 10:36 AM.]
Given the two choices sounds like you did the right thing. The edge of structural wood should not be bonded in direct contact with the hull from everything I've ever read on the subject. (mind you that's read. I've never done a stringer job...yet)
I beleive there are several ways to accomplish this. For example bedding the stringers in a flexible bed material versus leaving an air gap would have been an option.
When applying the glass to make a bond it is important to avoid "hard spots" as you say, the pros say "hard points" where the stress may be focused, the way around it is to lay up different widths of cloth, if you are using 4 layers the first would be the widest, then narrower and so on, you transfer the loads over a wider area, the stringer wood should not have a gap between the end of it and the transom, the finished joint will be tapered looking at a cross section..make sense?...Mick
I am a little confused . I am about to install my stringers and bulkheads in my boat. Now, when I tore out my liner/deck, there weren't any stringers supporting anything, just two blocks supporting the I/O (the liner was screwed into the hull in about 20 places). Do I need to be concerned with "hard spots", since the boat was originally constructed without stringers? When I look in the bilge, there is nothing touching the transom at all. Will having "hard spots" affect my situation in any way?
You are paying way more attention than most manufacturers. It is a good idea to eliminate hard spots, or points of stress, and it is as important in a repair as it is in the original building process. Congratulations.
Tom Marlowe, sales at Summerville Marine. Past Master Tech.
It's not quite on the same level, but I built a dinghy a few years ago (stitch & glue, nothign fancy) and one of the points they harped on was to be careful of creating hard points at the intersections.
The wood basically gets stitched together (I used plastic wire ties but back in the day they used wire) and then you filet the joint with thickened epoxy. If the 2 pieces of wood aren't touching each other, you won't have any hard spots. Then the joint itself takes and load and distributes it evenly.
If you're worried about the wood in the stringers creating hard spots, there are a couple of things you can do to reduce the stress concentrations.
1. Make sure you have decent fillets on your stringer-to-hull connection. 45 degree wood/foam fillet strips or a bonding putty fillet of at least 1" should be used.
2. Use a foam pad underneath the wood. This pad should have 45 degree bevels (thereby creating a fillet on each side) and t will be much softer on the hull than the wood (use low density urethane, PVC, or SAN foam).
3. Taper your glass tabs out from the stringer onto the hull laminate. I believe someone has already mentioned this.
I think it was RingLeader that showed all kinds of pictures with gussets custom shaped and fitted to the haul and transom then glassed into place.
I know on my 74 Grew has gussets and bulkheads firmly attached to the haul and transom but, the engine mount rails are not attached to the transom. I know that Grew was concidered a topquality boat of the period up here in these parts.
So my question here guys is: Stringers, engine mount rails or gussets what's the difference? Why some and not the others? Hard spots are hard spots right?
creating stringer "hard spots" 
. I am about to install my stringers and bulkheads in my boat. Now, when I tore out my liner/deck, there weren't any stringers supporting anything, just two blocks supporting the I/O (the liner was screwed into the hull in about 20 places). Do I need to be concerned with "hard spots", since the boat was originally constructed without stringers? When I look in the bilge, there is nothing touching the transom at all. Will having "hard spots" affect my situation in any way?
