Tips for replacing stringers

[CreekCruiser]

I am in the process of rebuilding my boat and I have a couple questions about the stringers in particular: a little backstory: I had a soft deck and took the advice of some forum members and cut it out to see what the damage was. The stringers in the front of the boat were pretty well trashed so I am cutting them out and replacing them. I currently have about a 1" lip around the perimeter of the deck and I am using this lip along with a straight edge and tape measure to try to duplicate my exiting stingers as they are much thinner in the front of the boat than in the back. Basically I marked the stringers every four inches and at that mark I lay the straight edge from "lip to lip" and then use my tape measure to measure down to the hull and record the measurement.

1: Does anyone know of an easier way to do this? The boat is almost 40 years old and the deck has warped in a couple places over the years. I plan on following the method in woodenglass' thread for stringer/deck replacement and eventually grind this lip off but I was hoping to use it as a constant to make my new stringers but it is far from constant.

2. The stringers slowly taper from 1 1/8" to 3". Any advice on how to lay this out on the new wood? What I have done so far is measure the existing stringer using the method described above and I have basically charted each stringer on 4" increments. For instance at 8" from the start of the stringer my height is 2", at 12" back it is 2 1/8" etc. is this a pretty sound way to do it? I figured I could use a jigsaw and get it pretty close and sand it smooth.

3. The measurements of the two stringers are not always an equal depth. For instance at 32" from the beginning of the stringers one side is 2 3/8" and the other side is 2 3/4". I know I mentioned that the remaining lip is kinda wavy and that might be the issue. What should I do in this situation? Should I cut each stringer exactly as I plot it or should I just average the two and cut them identically?

4: The boat is currently sitting on the trailer, I believe to be fairly well supported. Would it be better if I put the boat on the ground to minimize flexing or is this not an issue for a boat like mine?

Thanks for looking

 

[CreekCruiser]

Ya know, I type out my post all nice and neat and then when I hit "post" it shows up as this jumbled mess of words

 

[tpenfield]

Your method is fine. I would average the dimension of the stringer measurements (port/starboard) so in the example given 2-9/16" . . . your cutting will be about 1/8" accurate , so don't sweat the small fractions. You should end up with identical stringers. The bonding to the hull can take up any minor differences.

If the boat is well supported on a bunk trailer then no worries. If it is on a roller trailer, then slide some wood 2 x lumber in to support the load more evenly.

 

[glenn property of pam]

if you haven't removed all the stringers and you can lay a flat edge across the top then you can just do one at a time. i starter by laying a 2x2 across 3 stringers then marked the stringers on to the wood. then i used a chisel and cut one stringer out and traced around the stringer adding about a 1/4" . marked the tip of the stringer on the hull then ground out the area (grind off half the marker then redraw it before grinding all the marker off). i then nailed the 2 pieces of wood at right angles to the top of the new stringer (put a washer between the wood and stringer to add about 1/16 that will be filled later when fiberglass is added to top of the stringer). I layed the stringer in place then using a sharpy marked the bottom of the stringer by holding the marker against the hull on the outside and drawing a line. I then used a power plane and worked the stringer until the wood rested on the other stringers and there was about a 1/8" gap under the stringer that will be filled with pb. I glassed the stringer completely before doing the next one but that's your choose depending on where you are working.
Its a messy way to work because when you do the next stringer the dust from grinding will go all over the new stringer but you can cover that up so its not to bad. The advantage is the hull flex's less as it still has some stringers as support and I was working outside sealing and glassing one stringer at a time was a easier then having to try to do it all in one go.

 

[Kern Fischer]

I used a similar measurement method when replacing my stringers. You do not state how large your boat is. Mine was a 14 footer and there were four stringers.

I also measured from a floor reference plane down to the inside bottom. Then I shaped the stringers to these measurements. The shaping does not have to be extremely precise as I filled any gaps with resin. An important consideration is to get the tops of all the stringers so they are in a relatively flat plane to provide a flat floor.

To provide a bottom line that was as straight as possible, I fabricated a T shaped support to place under the hull where each stringer was located (one at a time) and blocked the hull so much of the weight was on this support. Then I bonded the new stringer in place. This assured that the bottom was as straight as possible. Even with this process I ended up with some waviiness on the bottom due to the original stringers not being bonded to the bottom and the effects of time on the fiberglass. At least now the bottom will be better supported and can be faired later to get a straight, smooth surface.

You can see pictures and a writeup of my stringer replacement at:http://www.classicglastron.com/phpbb/viewtopic.php?f=28&t=7510

Kern Fischer