Stringer to Transom Joint Question

[76SeaRay]

Do you run the stringer right up against the transom wood, fillet and tab that or do you need to put peanut butter between the stringer and transom wood to bed it?

Also, is it better or easier to lay a bead of peanut butter and then set the stringer into that or put in small foam spacers then "squeegy" the peanut butter under the stringer? Looking for the best result.

Thanks...

 

[Scott Danforth]

yes...... both work for the stringer to transom joint

for the stringer to hull, I put a line of PL to hold the stringers up a bit and a few days later, used a masons bag to pipe the PB in and then threw away the masons bag because I wasnt going to clean it. I made the fillets with a plastic spoon

 

[todhunter]

I cut my stringers as close as I could to the transom, but inevitably there was a small gap, so I just piped in PB and tabbed. I have been using the large icing piping bags from the grocery store - I can mix up 17 oz of resin and make PB and it fills the bag nicely.

 

[76SeaRay]

I was able to pretty much cut my stringers to match the transom without any gap hence my question. My aft inboard stringers just run from the transom to the front of the engine bay bulkhead then step in 3 inches on each side to run the stringers to the front of the boat. So, I was able to essentially build the stringers and bulkhead on my work table and drop it into the boat. I have angle iron running backwards from the forward stringers that I can clamp the aft stringers at the right height so I don't even need spacers.

 

[froggy1150]

Cheap Gallon ziploc bagsworj well too. Fill em up,twist the zipped end and cut the corner off to the size fillet you need and squeeze/twist away

 

[GSPLures]

Cheap Gallon ziploc bagsworj well too. Fill em up,twist the zipped end and cut the corner off to the size fillet you need and squeeze/twist away

I used ziplocs also, they worked good but make sure they are fully zipped! I grabbed the bag in a rush and dropped a quart of PB on the hull. Made a huge mess and I was covered in it by time the ordeal was done.

 

[76SeaRay]

So, I have two lengths of stringer 42 inches each and one length of bulkhead that is 54 inches in length to bed. This will be my first time at bedding stringers. Gap is about 1/2 inch in some places but closer to 1/4 inch in most places. How much poly resin to mix as peanut butter to bed those without a lot of waste or running out of time before it sets? I have an enclosed shop with a heat pump so I try to keep it in the 65 to 70 degree range.

 

[GSPLures]

What I did was used a couple tile spacers hot glued to keep in place to keep the stringer up. Set the stringers in place and PBed the front and rear to lock them down. Knocked the spacers out then piped the PB under. I mixed small amounts (half quart) at a time. Then once towards the end it is a little bit easier to determine how much with little waste.

 

[76SeaRay]

I put a thin layer of structural putty between the ends of the stringers and the transom glassed wood. I set the box into place and mixed a bit of peanut butter to spot areas to support it so I can pull the wedges and peanut butter and tab the whole thing. It has been a pain figuring out the right height of the stringers as the hull tends to rise in the back corners and the floor plywood didn't go all the way to the edge in the corners. So I ended up with 1/2 to 3/4 inch gap in some places between the stringer and hull once I set it as near as I could to the original height. Looks like I will have to bevel the edge of the floor plywood where it reaches sides. I hope the gap size is not an issue.

 

[todhunter]

Gap size isn't an issue - just means you'll need more PB in that area. Make sure you're making "hairy" PB with milled fibers in it.

I find the angle of a purpose-made piping bag is much better for dispensing PB than the 90-degree angle of a zip-lock bag with the corner cut off. The icing bag is also a stiffer material and the bag doesn't sag as much as a soft zip lock bag.

I also have a climate controlled shop and shoot for 65-70F. I found working in 17 oz batches was the best for me. It fits in the quart mixing cup and doesn't overflow when you start stirring and mixing. It takes 5cc of MEKP to achieve 1.0% - this is easy to measure when you're in a hurry. It fits nicely into the large icing piping bags. It's not such a big batch that it just takes off on you. For the transom I had my wife mixing batches while I applied them. For all the rest of the work, I mixed and applied myself, and only felt like it started to gel on me once in 3 months of doing some kind of resin work almost daily.

I didn't bed my entire stringers at once. I worked with my tabbing in ~50" lengths and piped in PB as I moved down the stringer, laying both layers of tabbing on the PB while it was still wet.

 

[76SeaRay]

Thanks for that info. It helps alot with the mixing. It has been driving my nuts trying to count drops of MEKP. I am using the 1/4 inch chopped strand and cabosil. I think I have been using a little too much chopped strand.

 

[76SeaRay]

Hmmmm, my laminating resin from West Marine says 12 drops of MEKP per ounce of resin (temp 70 to 90). My laminating resin from Total Boat says 8 drops MEKP per ounce of resin (temp 77). Do different resin manufacturers make it differently requiring different amounts? How does 5cc MEKP in 17 ounces of resin relate to drops these numbers?

Thanks...

 

[GSPLures]

Thanks for that info. It helps alot with the mixing. It has been driving my nuts trying to count drops of MEKP. I am using the 1/4 inch chopped strand and cabosil. I think I have been using a little too much chopped strand.

Go to a pharmacy and ask for a couple medicine syringes. They have cc measurements on them making it easy to mix whatever percentage that you want

 

[76SeaRay]

Thanks, I have syringes but wasn't sure about the number of drops per cc and why the number of drops are different between West Systems and Totalboat.

 

[todhunter]

I use the little medicine cups that come with kid's medicine. It's also what US Composites puts in with their MEKP. I also tried one of those MEKP dispensing squeeze bottles and didn't like it. Not sure about the different resin manufacturers and catalyst recommendations - I've only used US Composites resins. Also not sure how many drops per cc...google says 20, but that sounds like too much.

 

[GSPLures]

I use the little medicine cups that come with kid's medicine. It's also what US Composites puts in with their MEKP. I also tried one of those MEKP dispensing squeeze bottles and didn't like it. Not sure about the different resin manufacturers and catalyst recommendations - I've only used US Composites resins. Also not sure how many drops per cc...google says 20, but that sounds like too much.

Not sure about drops but a cc is a ml. 1 qt is approximately 1000ml. I normally do 10 cc per quart if mixing at 1%, 5 for half a quart etc. I have not had an issue with it kicking ( us composites and a local supply) except for when the temp got too low and I accidentally stepped on the tabbing and pulled it up. Eventually even that kicked in the garbage but was to late to save it once it pulled up.