transom and Stringers

[CT River Runner]

Can I do that with the Stringers as well? That would save time, resin, and cloth? And would it be ok to use pl premium to bed the Stringers in, and to use as a filet instead of using pb on the Stringers. I'm going to use pb for a filet on the transom like nurseman did.

 

[CT River Runner]

I found ACX In home depot today for 40 bucks a sheet! Straight as an arrow. Picking that up tomorrow morning, along with the tb 3 wood glue, decking screws, and some more 40 grit grinding sanding wheels. Can't wait, I'll post some pics tomorrow. My goal is to get the transom ply cut and prepped for glue for tomorrow. Then Sunday I want to glue it together.

 

[kcassells]

I found ACX In home depot today for 40 bucks a sheet! Straight as an arrow. Picking that up tomorrow morning, along with the tb 3 wood glue, decking screws, and some more 40 grit grinding sanding wheels. Can't wait, I'll post some pics tomorrow. My goal is to get the transom ply cut and prepped for glue for tomorrow. Then Sunday I want to glue it together.

Yes to all of your above questions..stringers, bulkheads etc.. But in regards to PL let's get get something straight right away. Read the instructions. Depending on temps, humidity etc pl needs to cure 100% before glassing up anything. My advice would be to stick some 1/4 rubber or foam under your stringers, use pb then and force it in, while moviing out the air bubbles and that will set up depending on your temps in like 4-8 hrs. Pl requires like 72 hrs cure time, expands and makes for a crappy fillet. IMHO. Others can chime in.
Make sure you seal all edges and any gaps/imperfections on the wood prior to glassing.

 

[kcassells]

Also seal all wood prior to setting. In regards again to above if you make the pb to use to set your woods then that will also be the time to make your fillets. I forget what are you using? Poly of Poxy? Poly pb requires @ 1/4 light amount of chopped strands for strength, poxy does not but I use it in there anyway.

 

[kcassells]

If you use pl on the transom then you should not glass it at all until cure time has passed for set up. Gases come out of pl which will bubble up your glass work. Don't forget to use cabosil if your making pb to thickin it up.

 

[CT River Runner]

I'm using an epoxy kevlar reinforced putty. It's a wet/dry 700. Product is from usa epoxy. Supposed to be some pretty tough s@$*.

 

[CT River Runner]

130 bucks a gal. Expensive, but I didn't want the transom to come off my boat while flying down the river

 

[jigngrub]

I can't see using tb3 when you've already got a far superior adhesive in the epoxy putty to bond the transom pieces together.

 

[rickryder]

I can't see using tb3 when you've already got a far superior adhesive in the epoxy putty to bond the transom pieces together.

Because Tite Bond III isn't $130 a gallon

 

[CT River Runner]

Ricky, how come your boat has foam and mine doesn't?

 

[rickryder]

I guess some boats built back in the day didn't get foam....personally I would put it in just in case

 

[jigngrub]

Because Tite Bond III isn't $130 a gallon

Yeah, that makes sense. Stick it to the skin with the expensive stuff and skimp on the laminating adhesive.

 

[jc55]

[h=5]Wet/Dry 700? epoxy[/h]

COMPRESSIVESTRENGTH .......... ASTMD695 10,500 psi​

TENSILESTRENGTH.................... ASTMD638 5,200 psi​

ABRASIONRESISTANCE.............​

CS-17WHEEL, 1 kgLOAD ............ ASTMD4060 0.20 gm loss​

WATERABSORPTION ................. ASTMD570 0.19 %​

(2 hour boil)​

FLEXURALSTRENGTH................ ASTMD790 4,900 psi​

SHORE D HARDNESS ................. ASTMD2240 88​

HEATDISTORTION...................... ASTMD649 122? F​

TEMPERATURE​

BONDSTRENGTHTOCONCRETE 100%concrete failure​

LAPSHEAR.................................. 2,200 psi​

**************************************************************************​

Fiberlay P-17 ISO Polyester Resin​

Cured Resin *2​

Test Value​

Tensile Strength 8,532 psi​

Flexural Strength 16,637 psi​

Flexural Modulus 597,215 psi​

Tensile Modulus 455,021 psi​

Barcol Hardness, 934-1 48​

Elongation 1.7%​

Heat Dist. Temp. 185?F-203?F​

Laminated Physical Properties *3​

Test Value​

Tensile Strength 16,352 psi​

Flexural Strength 25,168 psi​

Flexural Modulus 1,208,650 psi​

Tensile Modulus 1,109,114 psi​

Elongation 1.4%​

****************************************************************************************************************************
Titebond III

Bond Strength ASTM D-905 (On Hard Maple)

	Temperature	Strength	Wood Failure
	Room Temperature	4,000 psi	57%
	150?F Overnight	800 psi	0%

Not for continuous submersion or for use below the waterline. Not for structural or load bearing applications. Use when temperature, glue and materials are above 45?F. Store product below 75?F. Storage above this temperature may cause product to thicken and reduce the usable shelf life. If thickened, shake vigorously by firmly tapping bottle on a hard surface until product is restored to original form. Because of variances in the surfaces of treated lumber, it is a good idea to test for adhesion. For best results gluing exterior doors or exotic and oily woods, please contact out Technical Support Team at 1-800-347-4583. Read MSDS before use. KEEP FROM FREEZING. KEEP OUT OF THE REACH OF CHILDREN.

 

[Fun Times]

An interesting test. https://woodgears.ca/joint_strength/glue_methods.html

If whenever possible, tape your joints off to prevent squeeze out from being an issue in the first place.

There's no possible way to squeeze all of the adhesive out, not even with a 100 ton press. The tighter the squeeze the more durable and rigid the bond.

Here's an experiment for example:

Go outside and find a fresh pile of dog doo, get a pinch of it between your thumb and forefinger and squeeze them together as hard as you can. Now open them up, you can see and feel that there's still a coat of dog doo on both you finger and thumb. Now pinch your thumb and forefinger back together tightly and rotate them in a circular motion until all the dog doo feels like it's gone and where the thumb and finger meet now feels dry. Now open the thumb and forefinger, it looks dry and looks like all the dog doo is gone. Now smell them, yep it's still there!

If you haven't already bought the tb3 glue, I suggest using your epoxy putty to bond the 2 pieces of ply together. Epoxy is a superior adhesive compared to the wood and craft glues.

Uhhmmm you only need to clamp it hard enuf to get the pb to start oozing out around all the edges and ensure it's making good contact with the outer skin at all points. One of the reasons you thicken the resin to allow it to fill any irregularities in the glue up. If you squeeze it all out this won't occur. Do some searching on Glue starved joints and Resin Starved laminations and you'll get some knowledge about glueups and clamping. I personally would not advise using excessive clamping pressure when clamping the transom. If you do a proper job of spreading the PB on both the transom skin and the transom wood you will not have any voids in the PB some people like the idea of drilling holes in the transom to form a better mechanical bond, others don't. I'll leave that decision to you as well as the clamping pressure. It's your boat and your decision. Go with your Gut!!!

 

[jigngrub]

Did you happen to read this FT?

This:

The sheets are then patched, graded, glued together and then baked in a press at a temperature of at least 140 ?C (284 ?F), and at a pressure of up to 1.9 MPa (280 psi) (but more commonly 200 psi) to form the plywood panel.

Is from here:
http://en.wikipedia.org/wiki/Plywood

200-280 psi is a pretty tight squeeze when they laminate the plywood together in the factory. And when we bond 2 pieces plywood together to make an 1-1/2" piece for a transom, we're actually try to make an inch and a half piece of plywood that is at least as good as the two 3/4" pieces we're bonding together.

200 psi may not sound like a lot to some people, but when you add it up it's 7200 lbs on a 6" square.

I'll admit I didn't consider all the variables when I made my statement about not being able to squeeze all the adhesive out. A smooth hard surface and a thin consistency adhesive will evidently suffer from being over-clamped.

... but, when you take into consideration the coarse 2 C grade sides of plywood and the consistency of a good thick strong adhesive like thickened epoxy resin or PL Premium and the square footage of a boat transom... there's no way the average Schmoe backyard boat builder is going to squeeze all the thick adhesive out of the coarse textured joint between the 2 pieces of transom material. Not even if he parks his pickup truck on it!

JC55 also brought up a good point when he posted the specs to the Tite-bond 3 wood glue. The "Not for structural or load bearing applications" should rule it out as a suitable transom laminating material. While an I/O transom isn't very load bearing in that type boat, it is a structural member of the boat.

... but as the old saying goes, it's your boat build it any way you want.

 

[rickryder]

Yeah, that makes sense. Stick it to the skin with the expensive stuff and skimp on the laminating adhesive.

Being a carpenter by trade for many years I don't find wood glue to be cheap....inexpensive is more the word..... if glue bonds correctly you can't break that bond you will rip the wood apart first..

As far as load bearing the transom has to carry the the load yes but it's glassed into the boat and the glass and resin are carrying the load not the lamination of the plywood sheets IMO

J&G you don't need to get so defensive about my response I was just giving an answer that the glue was less cost than epoxy and will do the job...

 

[jigngrub]

Being a carpenter by trade for many years I don't find wood glue to be cheap....inexpensive is more the word..... if glue bonds correctly you can't break that bond you will rip the wood apart first..

I'm a carpenter by trade as well, over 30 yrs. in the construction trade.

Here's a homemade video that tests the strengths of 4 different adhesives from youtube:
https://www.youtube.com/watch?v=IY7hkCexNVY

Skip to the middle for the adhesives test. Not really scientific or exceptionally well done, but kinda interesting.

 

[jigngrub]

If you want a relatively inexpensive adhesive for boat building, go with PL Premium. You can get a case of twelve 28 oz. tubes for about $84 at Home Depot. That's 2-5/8 gallons @ about $32 per gallon and compared to $71 a gallon for epoxy resin or $130 a gallon for epoxy putty it's a bargain.

 

[rickryder]

That was interesting but they were doing tests more of shear load on a strong back glue joint not a lamination....plus they didn't use yellow wood glue in the test. also they soaked them in water something a glassed lam of a transom should never see or you have other problems It was a neat test thanks for sharing it :encouragement:

 

[JASinIL2006]

When I researched stuff for my resto, I recall looking at glues, and I thought the characteristics (e.g., resistance to softening via boil test) of TB III were pretty similar to the glues used in exterior plywoods.

Also, I think that warning that a product is not for use "below the waterline" means the product is not intended to be continuously immersed in water. I don't think it means you can't use it on the dry side of the hull encapsulated in fiberglass...