Adding bulkheads

The 18 foot OB boat I am working on restoring had only two stringers running in parrallell up the center of the hull. I want to do this right, in fact plan on keeping the ol' boat for a long time. can I...or should I add a few bulkheads between the new stringers? what if any are the guidelines?
Thanks in advance...Ok J

 

How sturdy the stringer grid is built is a good indication of what the designer intended this boat to handle. Small, light stringers are an indication of a hull designed for smooth water, inland lakes, etc; likewise, a beefy grid indicates that it's meant to take offshore pounding.
You can beef the thing up all you like, so long as you're careful to ensure that stresses are distributed appropriately. This boat might be designed to flex somewhat on impact- in which case simply adding bulkheads could be a problem. THe flip side of the coin is that it could have been built too light to start with and beefing it up would extend its life.
What is the hull made of? What about the stringers? (wood, encapsulated wood, glass, cored glass, etc.) The existing construction is going to be a key factor in your decisions.

 

Were -- is there any evidence that it had some? If not, no need. Check at boat shows and meets, see if they came with one. If you do not use full hp or drive like a idiot, don't worry. Enjoy.

 

Were -- is there any evidence that it had some? If not, no need. Check at boat shows and meets see if they came with one. If you do not use full hp or drive like a idiot don't worry. Enjoy.

 

Well...

The hull consists of woven roving fiberglass, the original stringers were fir, and the transom plywood. the original floor was uneven at the joints between the sections, and I would like to at least put a bulkhead in the areas underneath each joint. It is an old (1980) 18 ft Fiberform OB. and was nice and steady in the water prior to its rebuild which I am in the process of now. I have laminated the transom and will complete the encapsulation (epoxy) in the next few days, upon which I will begin the stringer and bulkhead construction. I have constructed a jig which places no stress on the hull at all and she is dead level. I just want to do it right, and the extra time is not an issue. So many questions...hah!

Thanks...J

 

OK, from what you describe there it sounds like the hull bottom was built just fine, but the floors supporting the sole were not. You're probably OK to beef the structure up somewhat, it will save you the trouble of fixing this again in 5 years when those joints start bending again. Probably the easiest route is to simply tear out the whole cockpit sole and put in all new frames, where they belong. Make sure all your bonds are good and solid, and solvent-wash the inside of the hull to get the wax and gunk off before you go glassing in new structural members. You say time's not an issue... this is very good, as the care you put into getting this restoration right will make your boat last 30 years instead of the 5 or so you'd get out of a hasty job.