Stringer question

« **on:** November 16, 2014, 01:05:12 AM »

What is the best way to get my old stringers out so that I can replace them. What is the most efficient way to accomplish this task. The stringers in my boat have so many holes and plugs in them it looks like moldy Swiss cheese.

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« **Reply #1 on:** November 16, 2014, 01:22:26 AM »

get yourself one of these oscillating saws. it cuts through fiberglass pretty easily and the blade allows you to get really close to the hull itself. it also doesnt generate a lot of dust. you're gonna be cutting through fiberglass and resin, which if you use a cutting wheel or grinding wheel its gonna go EVERYWHERE and you'll be itchy for days.

once you've cut the majority out use an angle grinder with a high grit flapper wheel (get a few of em) to knock down any high spots and get the surrounding area down to good solid clean hull glass, not tabbing from the old stringers or floor.

you can everything at harbor freight for cheap. be sure to use a 20% coupon.

« **Reply #2 on:** November 16, 2014, 10:38:32 AM »

while ka0tyk has good recommendations on tools....another tool would be a sawzall. puts out a little more dust but still far less than cutting wheel.
after stringers are removed, a grinder will work well for prepping the area for new glass.

take lots of pics....

« **Reply #3 on:** November 16, 2014, 01:14:22 PM »

Thanks guys I will pick one of those oscillating tools up. I will keep you guys updated on the work.

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« **Reply #4 on:** November 16, 2014, 01:35:51 PM »

Quote from: Mrblueeyesnick on November 16, 2014, 01:14:22 PM

Thanks guys I will pick one of those oscillating tools up. I will keep you guys updated on the work.

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10 bucks harbor freight. I've done 3 sets of stringers with one. 👍👍👍👍

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« **Reply #5 on:** November 16, 2014, 02:01:25 PM »

Quote from: jyeager on November 16, 2014, 01:35:51 PM

10 bucks harbor freight. I've done 3 sets of stringers with one. 👍👍👍👍

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BAM!

« **Reply #6 on:** November 17, 2014, 11:56:43 PM »

Ok so to keep you up to date. I got the oscillating saw and got the stringers out. The driver side looked ok but there was some water damage and whoever mounted the engine drilled 4 to 8 holes and tried to patch with dowels. The passenger side came out in three pieces and also had a bunch of holes drilled for the engine mounts. It was pretty bad. But now their out. All I have still to do is grind the fiberglass down where the stringers came out. Another question for you all is the stringers that came out were cut on the bottom to go with the bottom of the boat. Is there a way to put the stringers in without beveling the bottom of the wood? I know I will have to cut it to go up the bow. Thanks for the help everyone.

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« **Reply #7 on:** November 18, 2014, 10:53:13 AM »

And one other thing, what kind of wood do I use for the stringers. I know they are 2x6s but is there a certain type of wood I should get?

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« **Reply #8 on:** November 18, 2014, 10:53:27 AM »

You'll have to cut the wood to the shape of the boat. It's not that difficult. When you put the stingers back in on the wet glass, use some weight to hold them down. 👍👍👍👍👍👍👍

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« **Reply #9 on:** November 18, 2014, 11:10:21 AM »

And what kind of fiberglass do I use?

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« **Reply #10 on:** November 18, 2014, 11:13:36 AM »

ok, some of this could be considered opinion, some fact. here goes:

if you did enough searching, you will find that no, you dont have to bevel the wood to the contour of the hull. not doing so requires a 'pad' for lack of better word, for wood to sit on. this pad can be made from thickened resin(to a peanut butter consistency) and applied along where stringers would go about an inch wider on each side. while this mix is still wet, bed stringer down in it. just enough to make contact the full length without pushing stringer thru to touch hull.
you will need to have something made to hold stringer in place while thickened resin cures. this pad fills the void between hull and stringer without contouring the wood ( you still have trim wood as it gets closer to bow) and spreads the load out against the hull. the inch on each side gets a fillet to create a radius transition from stringer to hull. this fillet helps reduce air gaps down in the corners when laying up the glass. also, the curve is a stronger shape than the 90 degree( or more). speaking of glass....you should go out 6-8 inches past the stringers on each side on to the hull. take a look at the thickness of glass that was around old stringers. could be 1/4" thick, maybe 3/16. try to keep that thickness when laying up new glass. as you lay glass, each layer will should be roughly 2 inches short than the last. this puts the biggest layer first, second layer is shorter, third layer is shorter than second. some prefer to start with shortest layer first...and get bigger as you add layers. theres a debate with that. we wont get into it now. another method is to use small foam pieces to keep stringer off the hull roughly 1/4 inch. you will still need to brace stringer to keep it in place. from there, you layup your glass in the same way as the other method. this leave a gap between stringer and hull. which is said to use the radius in the glass to aid in absorbing hull shock and prevent hard spots. many approve of this....others dont. many prefer to have the wood against the hull. glass still needs a radius on transition between hull and stringer. other method is to contour the wood so it lays flush against the hull and tapers as it gets towards the bow. here, you still use thickened resin(some prefer a layer of wet glass) and apply it where stringer will lay, the width of stringer. when you lay stringer down, be sure it beds fully in resin. what squeezes out should get a fillet to create that radius transition. add more if needed. brace stringer to keep it in place while resin cures. afterward, you can prep for glass lay up in the same fashion. all methods have there merits. up to you to decide which one is good for you.
however! one thing has been pretty unanimous and thats hull set up prior to installing stringers. if youre hull is still on trailer, you need to prop it up, off trailer bunks. to keep it simple, place a tall jack stand, blocks of wood, something stable!, under the transom corners. for the front, place a another stable block under the keel just about as far forward as your most forward trailer bunk. what you have should be a three point stand. this will let hull relax and its from here where you should prep/shape new stringer for hull. bunks on trailer push up on hull....even just an inch, when stringers are removed. this creates an unwanted hull contour that would be locked in place with installation of new stringers. no doubt others will chime in. up to you to choose a method. do some research, plenty of info on stringer replacement(for a boat, not stairs

) good luck, keep us updated.
It's more important to have good wood, then select a specific species. You want wood that has a straight grain, free from knots or if there are knots, they should be very small and tight. Find some lumber that has a tight grain, with close annual ring spacing. theres actually a term for this type of dimensional lumber....i cant think of the name right now. sorry for long post.

« **Reply #11 on:** November 18, 2014, 02:34:19 PM »

Quote from: JARVIS on November 18, 2014, 11:13:36 AM

ok, some of this could be considered opinion, some fact. here goes:

if you did enough searching, you will find that no, you dont have to bevel the wood to the contour of the hull. not doing so requires a 'pad' for lack of better word, for wood to sit on. this pad can be made from thickened resin(to a peanut butter consistency) and applied along where stringers would go about an inch wider on each side. while this mix is still wet, bed stringer down in it. just enough to make contact the full length without pushing stringer thru to touch hull.
you will need to have something made to hold stringer in place while thickened resin cures. this pad fills the void between hull and stringer without contouring the wood ( you still have trim wood as it gets closer to bow) and spreads the load out against the hull. the inch on each side gets a fillet to create a radius transition from stringer to hull. this fillet helps reduce air gaps down in the corners when laying up the glass. also, the curve is a stronger shape than the 90 degree( or more). speaking of glass....you should go out 6-8 inches past the stringers on each side on to the hull. take a look at the thickness of glass that was around old stringers. could be 1/4" thick, maybe 3/16. try to keep that thickness when laying up new glass. as you lay glass, each layer will should be roughly 2 inches short than the last. this puts the biggest layer first, second layer is shorter, third layer is shorter than second. some prefer to start with shortest layer first...and get bigger as you add layers. theres a debate with that. we wont get into it now. another method is to use small foam pieces to keep stringer off the hull roughly 1/4 inch. you will still need to brace stringer to keep it in place. from there, you layup your glass in the same way as the other method. this leave a gap between stringer and hull. which is said to use the radius in the glass to aid in absorbing hull shock and prevent hard spots. many approve of this....others dont. many prefer to have the wood against the hull. glass still needs a radius on transition between hull and stringer. other method is to contour the wood so it lays flush against the hull and tapers as it gets towards the bow. here, you still use thickened resin(some prefer a layer of wet glass) and apply it where stringer will lay, the width of stringer. when you lay stringer down, be sure it beds fully in resin. what squeezes out should get a fillet to create that radius transition. add more if needed. brace stringer to keep it in place while resin cures. afterward, you can prep for glass lay up in the same fashion. all methods have there merits. up to you to decide which one is good for you.
however! one thing has been pretty unanimous and thats hull set up prior to installing stringers. if youre hull is still on trailer, you need to prop it up, off trailer bunks. to keep it simple, place a tall jack stand, blocks of wood, something stable!, under the transom corners. for the front, place a another stable block under the keel just about as far forward as your most forward trailer bunk. what you have should be a three point stand. this will let hull relax and its from here where you should prep/shape new stringer for hull. bunks on trailer push up on hull....even just an inch, when stringers are removed. this creates an unwanted hull contour that would be locked in place with installation of new stringers. no doubt others will chime in. up to you to choose a method. do some research, plenty of info on stringer replacement(for a boat, not stairs ) good luck, keep us updated.
It's more important to have good wood, then select a specific species. You want wood that has a straight grain, free from knots or if there are knots, they should be very small and tight. Find some lumber that has a tight grain, with close annual ring spacing. theres actually a term for this type of dimensional lumber....i cant think of the name right now. sorry for long post.

Thanks for all the info. There is a lot to absorb but I will do my research before moving foreword. I am learning a lot taking on this project and I could use all the input that I can get. I want to have this boat back up and running by spring. I would really like to get out to some of the outings and meet all of you.

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« **Reply #12 on:** November 18, 2014, 07:36:15 PM »

Take your time. Do it right once.

« **Reply #13 on:** November 18, 2014, 07:42:23 PM »

That it. I'm a perfectionist so if it's not right I won't be happy😀

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« **Reply #14 on:** November 18, 2014, 08:16:22 PM »

What you want to avoid are hard spots. Example: a sharp edge of wood against Hull. where wood can exert high pressure on a small surface. Think of a pencil pushing thru paper....now lay pencil on it's side and try to push thru paper. Get it? Hard spots or hard points can eventually crack gel coat and has the potential to damage glass.

« **Reply #15 on:** November 18, 2014, 08:35:03 PM »

You may have gotten some odd advice here...

The only parts you don't want pushing against the fiberglass is when it is perpendicular.

The stringers are parallel. There should be no air gap between the hull and the stringers. In other words glassed up tight. The better the fit, the stronger the structure.

You can use virtually anything to keep the parts straight while they cure.

Good luck and be sure to get the hull blocked up either on a dolly or the trailer, you don't want it simply resting on the bunks.

GT

« **Reply #16 on:** November 18, 2014, 09:04:39 PM »

Quote from: GT Jets on November 18, 2014, 08:35:03 PM

You may have gotten some odd advise here...

GT

Perhaps the pencil analogy was less than ideal...

However, the point was to ensure the stringer was flush against Hull, without any corners or edges applying more pressure, at that specific point of contact. About the other methods of bedding stringers.... those were the methods found upon researching how to bed stringers. Even read about products, such as foam stringers... and pieces of foam already trimmed to Hull deadrise and were flat on top so no contouring of wood or foam stringer needed....aside from tapering stringer as it nears the bow.
I only mentioned those methods as they were the most popular ways to bed stringers when I searched for mine. no recommendations were made in.regards to those methods.
Debates were made about all those methods as well as whether layup should be largest to smallest layer or vise versa starting from Hull up.
By no means am I attempting to dispute your or anyone's info. This is just info I've picked up along the way from many sites....including here.

I'd like to hear which part was odd...and why...I'm always willing to learn more.

« **Reply #17 on:** November 18, 2014, 09:09:25 PM »

GT, pm sent....

« **Reply #18 on:** November 18, 2014, 09:17:59 PM »

Quote from: JARVIS on November 18, 2014, 09:04:39 PM

Perhaps the pencil analogy was less than ideal...

However, the point was to ensure the stringer was flush against Hull, without any corners or edges applying more pressure, at that specific point of contact. About the other methods of bedding stringers.... those were the methods found upon researching how to bed stringers. Even read about products, such as foam stringers... and pieces of foam already trimmed to Hull deadrise and were flat on top so no contouring of wood or foam stringer needed....aside from tapering stringer as it nears the bow.
I only mentioned those methods as they were the most popular ways to bed stringers when I searched for mine. no recommendations were made in.regards to those methods.
Debates were made about all those methods as well as whether layup should be largest to smallest layer or vise versa starting from Hull up.
By no means am I attempting to dispute your or anyone's info. This is just info I've picked up along the way from many sites....including here.

I'd like to hear which part was odd...and why...I'm always willing to learn more.

Wasn't poking dead at you.. Just the part about the wood not being in direct contact with anything hit me strange...

The resins that the stringer will be bedded to will be several times harder than a piece of clear KD Fir. I see now where you were going with the pokey comment.

Just be sure that there are no voids between the hull and the stringer material. You also don't want the bedding material to be too gooey.. I like a nice smooth cake icing consistency...

I like where this info is headed. Sometimes it is hard to explain exactly what you mean..

No harm, no foul.

Carry on fellow artists of the squirting boat... LMAO

GT

« **Reply #19 on:** November 18, 2014, 09:29:28 PM »

thank you kindly sir

« **Reply #20 on:** November 19, 2014, 12:22:56 AM »

pm sent again GT

« **Reply #21 on:** November 19, 2014, 02:06:51 PM »

Thanks guys. What kind of resin so you suggest? What do I need to get for the bedding? Like I said this my first time doing this so I want to know what you guys might use

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« **Reply #22 on:** November 19, 2014, 07:42:07 PM »

well....again....i may catch heat on this one too....haha.

so heres my list from good to best, with some pros and cons to each. (again, my opinion)

polyester resin.
Uses: General purpose, Hand lay-up, boat hulls.
Pros:
- Easy to work with, catalyize with mekp. there is a ratio to follow, but it can be increased or decrease to adjust cure times(within reason) without ill effects.
- High thixotropic index (less likely to run on vertical surfaces)
- available with Wax or curing agent to prevent surface tackiness, also available as a laminating resin which has no wax, leaves a tacky surface.
- Inexpensive

Cons:
- The wax must be sanded off prior to applying subsequent layers...otherwise wax acts like a mold release and added layer(s) will delaminate.

Vinylester (VE)
Uses: Gas tanks, Boat hulls, Heat resistant applications.
Pros:
- Extremely tough
- Corrosion Resistant
- Heat Resistant(dont remember how hot, but its not super high)
- catalyize with mekp

Cons:
- 3 month shelf-life

epoxy resin:
Uses: Structural application, High-strength projects, Adhesion to metal, wood, fiberglass, many plastics.
Pros:
- High strength properties
- Superior to other room-temperature epoxies
- Maximizes the physical properties of carbon fiber, KEVLAR® and fiberglass
- Multiple cure options
- Can be used in vacuum infusion applications
- Easy to handle, must use accurate mix ratio, can not be sped up or slowed down by adding more or less hardener. fast and slow hardeners available. also, pumps available to disperse accurate mix ratios

Cons:
- doesnt wet out chopped strand mat as polyester resin.
- Not UV stable. Will deteriorate without a top coat when exposed to UV rays. additives available.
- thin enough to run on vertical surfaces/layups leaving glass material dry or starved of resin...and pools at the bottom.
- must use accurate mix ratio, can not be sped up or slowed down by adding more or less hardener.

with that, epoxy is gonna give you the strongest bond and layup. followed by vinylester, then polyester. also in that order as far as cost.
most of our boats were made with polyester and should be just fine for your project. poly can cure in your pot if your not quick enough(so can the others). and/or if you use too much catalyst. it wets out fiberglass just fine. you can also mix in thickeners like cabosil, chopped strand mat, etc. same for epoxy and vinylester. epoxy wets out CSM but just the glass part, the binders(glue) use to make the mat is not broken down by epoxy, so it remains sort of stiff and doesnt like to go around/over curves/corners. so good for flat to slightly curved surfaces. no problems with fiberglass cloths. vinlyesters and polyesters works fine with csm and cloths. also....if you choose epoxy, you should finish the job with epoxy....as polyester doesnt like to stick to epoxy....and may delaminate. vinylester sticks better to epoxy, but best to stick with epoxy if thats your choice. vinylester and polyester laminate well together. however....epoxy, being such a strong adhesive....with stick just fine to .....just about anything.

for bedding, you need a plan of attack, resin & catalyst, fiberglass, wood for stringer, mixing cups and sticks, 2-3 inch chip brush(es), acetone(to clean cups, brushes etc-before resin gels), latex/nitrile gloves, respirator-depending on resin used, old shoes and clothes...once resin gets on them...it aint coming off, a six pack, some music and maybe a buddy to lend a hand. last 3 items optional...haha. as far as fiberglass weights...ill check my notes on what i used. but im sure someone here has already posted that info...search for stringer replacement, repair, etc.

« **Reply #23 on:** November 20, 2014, 02:04:26 PM »

I liked the pencil analogy. Good info guys....👍👍👍

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« **Reply #24 on:** November 30, 2014, 06:44:03 PM »

Hit up ganahl lumber in corona. Use top grade doug fir #1. I paid $90 for 2 -2"×6"×12' pieces of lumber .

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