TIMBER MAST ADHESIVES

[sgunns]

We are building a new 85 ft x 250 dia oregon hollow tapered mast in segmented construction. Various "experts" have recommended different adhesives, some with benefits such as working time, etc.

What is the best adhesive, and why is it the best?

Steve Gunns
Sydney
Australia

[sgunns]

We are building a new 85 ft x 250 dia oregon hollow tapered mast in segmented construction. Various "experts" have recommended different adhesives, some with benefits such as working time, etc.

What is the best adhesive, and why is it the best?

Steve Gunns
Sydney
Australia

[sgunns]

We are building a new 85 ft x 250 dia oregon hollow tapered mast in segmented construction. Various "experts" have recommended different adhesives, some with benefits such as working time, etc.

What is the best adhesive, and why is it the best?

Steve Gunns
Sydney
Australia

[cs]

While I've built several small mast and spars, I've never built one to that scale. But I will add my 2 cents anyway.

I've not built a hollow mast, but while making solid mast I've had to do a build up using several layers of fir. I've used Tightbond II and thickned epoxy. Both have worked well for me.

The Tightbond makes nice thin glue lines, but there has been questions of whether or not it holds up well when in a wet enviroment. I've had no problems.

The epoxy, while making more noticiable glue lines, provides an outstanding bond that is not affected as much by water. It is also gap filling so your joints don't have to be as clean.

Chad

[cs]

While I've built several small mast and spars, I've never built one to that scale. But I will add my 2 cents anyway.

I've not built a hollow mast, but while making solid mast I've had to do a build up using several layers of fir. I've used Tightbond II and thickned epoxy. Both have worked well for me.

The Tightbond makes nice thin glue lines, but there has been questions of whether or not it holds up well when in a wet enviroment. I've had no problems.

The epoxy, while making more noticiable glue lines, provides an outstanding bond that is not affected as much by water. It is also gap filling so your joints don't have to be as clean.

Chad

[cs]

While I've built several small mast and spars, I've never built one to that scale. But I will add my 2 cents anyway.

I've not built a hollow mast, but while making solid mast I've had to do a build up using several layers of fir. I've used Tightbond II and thickned epoxy. Both have worked well for me.

The Tightbond makes nice thin glue lines, but there has been questions of whether or not it holds up well when in a wet enviroment. I've had no problems.

The epoxy, while making more noticiable glue lines, provides an outstanding bond that is not affected as much by water. It is also gap filling so your joints don't have to be as clean.

Chad

[Mrleft8]

Oooooh! This is gonna be FUN to watch! :D
I think you'll get as many different opinions on which adhesive is "best", and "why" as you will answers.
Have you contacted any of the big timber spar makers and asked them what they use?

[Mrleft8]

Oooooh! This is gonna be FUN to watch! :D
I think you'll get as many different opinions on which adhesive is "best", and "why" as you will answers.
Have you contacted any of the big timber spar makers and asked them what they use?

[Mrleft8]

Oooooh! This is gonna be FUN to watch! :D
I think you'll get as many different opinions on which adhesive is "best", and "why" as you will answers.
Have you contacted any of the big timber spar makers and asked them what they use?

[Ian McColgin]

This is a good size to make marvelous use of the bird's mouth approach if you're going round. Were I doing it, I'd scarf up the eight lengths first, then taper and mill them, and finally assemble the whole unit at once. This approach will actually be easier to make than a box construction and far easier than alternative hollow round constructions.

In any event, while there are many excellent adhesives about, few are as tenacious and forgiving as good epoxy.

Given that you raise the question, we might gather that you're not used to adhesive construction. It would be well to practice on small cheap structures so that you have some skills in coping with cure time, clamping to avoid slippage, and all that before you spread a couple hundred square feet of wood with goodge.

G'luck.

[Ian McColgin]

This is a good size to make marvelous use of the bird's mouth approach if you're going round. Were I doing it, I'd scarf up the eight lengths first, then taper and mill them, and finally assemble the whole unit at once. This approach will actually be easier to make than a box construction and far easier than alternative hollow round constructions.

In any event, while there are many excellent adhesives about, few are as tenacious and forgiving as good epoxy.

Given that you raise the question, we might gather that you're not used to adhesive construction. It would be well to practice on small cheap structures so that you have some skills in coping with cure time, clamping to avoid slippage, and all that before you spread a couple hundred square feet of wood with goodge.

G'luck.

[Ian McColgin]

This is a good size to make marvelous use of the bird's mouth approach if you're going round. Were I doing it, I'd scarf up the eight lengths first, then taper and mill them, and finally assemble the whole unit at once. This approach will actually be easier to make than a box construction and far easier than alternative hollow round constructions.

In any event, while there are many excellent adhesives about, few are as tenacious and forgiving as good epoxy.

Given that you raise the question, we might gather that you're not used to adhesive construction. It would be well to practice on small cheap structures so that you have some skills in coping with cure time, clamping to avoid slippage, and all that before you spread a couple hundred square feet of wood with goodge.

G'luck.

[paladin]

additional research into the epoxy characteristics is warranted....a slightly flexible epoxy would appear more desirable then a really rigid..hard one......

[paladin]

additional research into the epoxy characteristics is warranted....a slightly flexible epoxy would appear more desirable then a really rigid..hard one......

[paladin]

additional research into the epoxy characteristics is warranted....a slightly flexible epoxy would appear more desirable then a really rigid..hard one......

[John B]

epoxy V resorcinol.
something to think about... this is anectdotal... is where you're going with the boat.
I have been told of epoxy glued masts letting go progressively in the islands due to the heat. One guy I met some time ago, had his mast out in order to split it and re glue with resorcinol for that reason. I'm sure there has been significant upgrades in the epoxy technology since then but its worth considering and researching if you're off north.

[John B]

epoxy V resorcinol.
something to think about... this is anectdotal... is where you're going with the boat.
I have been told of epoxy glued masts letting go progressively in the islands due to the heat. One guy I met some time ago, had his mast out in order to split it and re glue with resorcinol for that reason. I'm sure there has been significant upgrades in the epoxy technology since then but its worth considering and researching if you're off north.

[John B]

epoxy V resorcinol.
something to think about... this is anectdotal... is where you're going with the boat.
I have been told of epoxy glued masts letting go progressively in the islands due to the heat. One guy I met some time ago, had his mast out in order to split it and re glue with resorcinol for that reason. I'm sure there has been significant upgrades in the epoxy technology since then but its worth considering and researching if you're off north.

[RonW]

Technical data sheet on resorcinol.

http://www.dap.com/techbulletins/00030205.pdf

Lots of solid info on resorcinol, it does exsplain moisture content of lumber for glueing, as well as temperatures. Strong, tuff glue, but it doesn't mention flexibility of glueline, might want to contact manufacturer.

[RonW]

Technical data sheet on resorcinol.

http://www.dap.com/techbulletins/00030205.pdf

Lots of solid info on resorcinol, it does exsplain moisture content of lumber for glueing, as well as temperatures. Strong, tuff glue, but it doesn't mention flexibility of glueline, might want to contact manufacturer.

[RonW]

Technical data sheet on resorcinol.

http://www.dap.com/techbulletins/00030205.pdf

Lots of solid info on resorcinol, it does exsplain moisture content of lumber for glueing, as well as temperatures. Strong, tuff glue, but it doesn't mention flexibility of glueline, might want to contact manufacturer.

[Ian McColgin]

Goblin's old hollow masts were probably first laid up with some sort of casein glue and may have been repaired in the '50's with resourcinol. When I had to repair some rot in the foremast, scarfing in about 6' of new structure, and incidentally cleaning up glue failures along both masts, I used epoxy.

Epoxy's wonderful gap filling should not be carried too far in masts as a thin glue line will take lots of flexing stress that a thick glue line will not. Even WEST! The brothers have built what amount to wooden springs to give some live action to the amas of their high tech tris and report no fatigue failure.

Regarding heat - the tropical heat can be intense and if you want that varnished look, have lots of UV filtering very high gloss varnish. The gloss will reflect out ever so much. Or, as one cruiser I know does, just paint them white over the varnish when in the tropics and back to varnish when summering in New England.

[Ian McColgin]

Goblin's old hollow masts were probably first laid up with some sort of casein glue and may have been repaired in the '50's with resourcinol. When I had to repair some rot in the foremast, scarfing in about 6' of new structure, and incidentally cleaning up glue failures along both masts, I used epoxy.

Epoxy's wonderful gap filling should not be carried too far in masts as a thin glue line will take lots of flexing stress that a thick glue line will not. Even WEST! The brothers have built what amount to wooden springs to give some live action to the amas of their high tech tris and report no fatigue failure.

Regarding heat - the tropical heat can be intense and if you want that varnished look, have lots of UV filtering very high gloss varnish. The gloss will reflect out ever so much. Or, as one cruiser I know does, just paint them white over the varnish when in the tropics and back to varnish when summering in New England.

[Ian McColgin]

Goblin's old hollow masts were probably first laid up with some sort of casein glue and may have been repaired in the '50's with resourcinol. When I had to repair some rot in the foremast, scarfing in about 6' of new structure, and incidentally cleaning up glue failures along both masts, I used epoxy.

Epoxy's wonderful gap filling should not be carried too far in masts as a thin glue line will take lots of flexing stress that a thick glue line will not. Even WEST! The brothers have built what amount to wooden springs to give some live action to the amas of their high tech tris and report no fatigue failure.

Regarding heat - the tropical heat can be intense and if you want that varnished look, have lots of UV filtering very high gloss varnish. The gloss will reflect out ever so much. Or, as one cruiser I know does, just paint them white over the varnish when in the tropics and back to varnish when summering in New England.

[RonW]

I will add this chart, very informative,

http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch09.pdf

Half way down, chart 9-2 you will find interesting, as well as at the end, chart 9-12 as to the lifespan of different glues.
Very informative and seems that resorcinol has a lot going for it.

[RonW]

I will add this chart, very informative,

http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch09.pdf

Half way down, chart 9-2 you will find interesting, as well as at the end, chart 9-12 as to the lifespan of different glues.
Very informative and seems that resorcinol has a lot going for it.

[RonW]

I will add this chart, very informative,

http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch09.pdf

Half way down, chart 9-2 you will find interesting, as well as at the end, chart 9-12 as to the lifespan of different glues.
Very informative and seems that resorcinol has a lot going for it.

[Bruce Hooke]

The three big downsides with Resorcinol are, as I see it:

A. It is purple so you can't really use it on wood that will be varnished.

B. It is not at all gap-filling so your joints have to fit together very nicely.

C. The official specs call for very high clamping pressures, whereas with epoxy you basically just need to achieve contact.

[Bruce Hooke]

The three big downsides with Resorcinol are, as I see it:

A. It is purple so you can't really use it on wood that will be varnished.

B. It is not at all gap-filling so your joints have to fit together very nicely.

C. The official specs call for very high clamping pressures, whereas with epoxy you basically just need to achieve contact.

[Bruce Hooke]

The three big downsides with Resorcinol are, as I see it:

A. It is purple so you can't really use it on wood that will be varnished.

B. It is not at all gap-filling so your joints have to fit together very nicely.

C. The official specs call for very high clamping pressures, whereas with epoxy you basically just need to achieve contact.

[sr. jigaboni]

resorcinol is used to make split cane bamboo flyrods. These things depend on glue for their structure, being, essentially, a little tiny mast used for whipping flies across the pond(or stream, or bay). At least on this small scale, and for at least a lifetime, resorcinol is PLENTY flexible.

I hope your mast never flexes as much as my 12 foot trout pole!

ps it's varnished, if that matters, and has taken more dunking than your mast should, too.

[sr. jigaboni]

resorcinol is used to make split cane bamboo flyrods. These things depend on glue for their structure, being, essentially, a little tiny mast used for whipping flies across the pond(or stream, or bay). At least on this small scale, and for at least a lifetime, resorcinol is PLENTY flexible.

I hope your mast never flexes as much as my 12 foot trout pole!

ps it's varnished, if that matters, and has taken more dunking than your mast should, too.

[sr. jigaboni]

resorcinol is used to make split cane bamboo flyrods. These things depend on glue for their structure, being, essentially, a little tiny mast used for whipping flies across the pond(or stream, or bay). At least on this small scale, and for at least a lifetime, resorcinol is PLENTY flexible.

I hope your mast never flexes as much as my 12 foot trout pole!

ps it's varnished, if that matters, and has taken more dunking than your mast should, too.

[Cuyahoga Chuck]

The only common waterproof glues are epoxy and resorcinol.
Epoxy's only achilles heel is high heat. But there are special epoxies that can tolerate several hundred degrees or more easily. Epoxy is noted for it's good bond with almost any kind of fit.
Resorcinol's achilles heel is it's demand for tight fits. Thick glue lines are either problematic or outright weak.
The inability to do precise joinery leaves a lot of us in the epoxy camp.
Every time I paddle out my life is in the Gudgeon Bros. hands.
Charlie

[Cuyahoga Chuck]

The only common waterproof glues are epoxy and resorcinol.
Epoxy's only achilles heel is high heat. But there are special epoxies that can tolerate several hundred degrees or more easily. Epoxy is noted for it's good bond with almost any kind of fit.
Resorcinol's achilles heel is it's demand for tight fits. Thick glue lines are either problematic or outright weak.
The inability to do precise joinery leaves a lot of us in the epoxy camp.
Every time I paddle out my life is in the Gudgeon Bros. hands.
Charlie

[Cuyahoga Chuck]

The only common waterproof glues are epoxy and resorcinol.
Epoxy's only achilles heel is high heat. But there are special epoxies that can tolerate several hundred degrees or more easily. Epoxy is noted for it's good bond with almost any kind of fit.
Resorcinol's achilles heel is it's demand for tight fits. Thick glue lines are either problematic or outright weak.
The inability to do precise joinery leaves a lot of us in the epoxy camp.
Every time I paddle out my life is in the Gudgeon Bros. hands.
Charlie

[RonW]

SGUNNS- So, after your research, opinions,and emails, which way are you leaning and WHY?

In the interest of muddying up the waters, here is also a very interesting chart comparing polyurethane glue strength to resorcinol.
Well worth reading and with some surprising test results.

http://www.fpl.fs.fed.us/documnts/pdf1998/vick98b.pdf

The sheer strength of the glue joints are of interest more then the wood failure of wet joints.

[ 01-31-2005, 12:31 PM: Message edited by: RonW ]

[RonW]

SGUNNS- So, after your research, opinions,and emails, which way are you leaning and WHY?

In the interest of muddying up the waters, here is also a very interesting chart comparing polyurethane glue strength to resorcinol.
Well worth reading and with some surprising test results.

http://www.fpl.fs.fed.us/documnts/pdf1998/vick98b.pdf

The sheer strength of the glue joints are of interest more then the wood failure of wet joints.

[ 01-31-2005, 12:31 PM: Message edited by: RonW ]

[RonW]

SGUNNS- So, after your research, opinions,and emails, which way are you leaning and WHY?

In the interest of muddying up the waters, here is also a very interesting chart comparing polyurethane glue strength to resorcinol.
Well worth reading and with some surprising test results.

http://www.fpl.fs.fed.us/documnts/pdf1998/vick98b.pdf

The sheer strength of the glue joints are of interest more then the wood failure of wet joints.

[ 01-31-2005, 12:31 PM: Message edited by: RonW ]

[Bruce Hooke]

Originally posted by RonW:
The sheer strength of the glue joints are of interest more then the wood failure of wet joints.Why do you say this? In any marine application I would certainly be concerned about the problems polyurethane had in the tests with wet wood and with wet-dry cycling. A mast should stay relatively dry, but problems have been known to occur that leave areas of the mast wet for a while. Based on my quick reading of the test results, polyurethanes are certainly not a good choice for wood that will regularly be saturated with water.

[Bruce Hooke]

Originally posted by RonW:
The sheer strength of the glue joints are of interest more then the wood failure of wet joints.Why do you say this? In any marine application I would certainly be concerned about the problems polyurethane had in the tests with wet wood and with wet-dry cycling. A mast should stay relatively dry, but problems have been known to occur that leave areas of the mast wet for a while. Based on my quick reading of the test results, polyurethanes are certainly not a good choice for wood that will regularly be saturated with water.

[Bruce Hooke]

Originally posted by RonW:
The sheer strength of the glue joints are of interest more then the wood failure of wet joints.Why do you say this? In any marine application I would certainly be concerned about the problems polyurethane had in the tests with wet wood and with wet-dry cycling. A mast should stay relatively dry, but problems have been known to occur that leave areas of the mast wet for a while. Based on my quick reading of the test results, polyurethanes are certainly not a good choice for wood that will regularly be saturated with water.

[Bob Smalser]

Thanks for posting the USDA poly vs resorcinol tests.

Very interesting...but when you read it closely, they don't compare at all...especially for lamination.

I like resorcinol, but I'd have a difficult time getting 85' of space heated sufficiently to the 70 degrees or so required for a reliable cure. As a consequence, I'd be talking to an epoxy expert about what flavor to use to lay up 85' of birdsmouth spar.

[Bob Smalser]

Thanks for posting the USDA poly vs resorcinol tests.

Very interesting...but when you read it closely, they don't compare at all...especially for lamination.

I like resorcinol, but I'd have a difficult time getting 85' of space heated sufficiently to the 70 degrees or so required for a reliable cure. As a consequence, I'd be talking to an epoxy expert about what flavor to use to lay up 85' of birdsmouth spar.

[Bob Smalser]

Thanks for posting the USDA poly vs resorcinol tests.

Very interesting...but when you read it closely, they don't compare at all...especially for lamination.

I like resorcinol, but I'd have a difficult time getting 85' of space heated sufficiently to the 70 degrees or so required for a reliable cure. As a consequence, I'd be talking to an epoxy expert about what flavor to use to lay up 85' of birdsmouth spar.

[PeterSibley]

The job is in Australia Bob, the working temperature is not a problem .

[PeterSibley]

The job is in Australia Bob, the working temperature is not a problem .

[PeterSibley]

The job is in Australia Bob, the working temperature is not a problem .

[PeterSibley]

The job is in Australia Bob, the working temperature is not a problem .

[PeterSibley]

The job is in Australia Bob, the working temperature is not a problem .

[PeterSibley]

The job is in Australia Bob, the working temperature is not a problem .

[RonW]

I read through this several times and had to think about it before some interesting facts finally appeared. And I was a bit surprised.

Think we all can agree that resorcinol is our strongest wood glue, dry or wet, maybe not the easiest or most desirable to use in all situations, but still the strongest. That is why they used resorcinol as a comparison for polyurethane glues.

They used 2 woods, yellow birch and douglas fir.
On the d.f. in the dry test, the polyurethane had a sheer strength of 1200, while resorcinol had 900 lbs of sheer strength, poly had almost a 100% wood failure. In both cases more then resorcinol.

In the next 3 tests which all are wet tests including a boil test, it appears that poly falls way behind resorcinol. Resorcinol has about 2 times as much wood failure in d.f. and almost 4 times as much in yellow birch as does the poly.
Sounds convincing for the resorcinol, But hold it. Look at the sheer strength in the same tests, and this is where it gets interesting.

The poly failed at only about 10% less sheer strength then did the resorcinol.
So it would appear that poly is stronger then resorcinol in dry wood joints and about 90% as strong as resorcinol under wet wood conditions.
After all isn't the real test of a glue joint the actual lbs of sheer strength that it actually takes to rip the joint apart.

As for the greater difference in wood failure in wet wood for the resorcinol.When you think about it, resorcinol requires tight fits and tight clamping, and results in a 5 or 6 thousands glue line. Poly would have a 25 thousands glue line or about 5 times thicker glue line.It would be much easier for the glue line to fail with a much thicker glue line, but again bottom line is - what is the actual sheer strength to pull apart the glue line, and poly only has about 10% less strength then resorcinol in wet woods.

It would make sense that you use metal fasteners as well in wet conditions.

I looked in this site but, as of yet have not found a test comparing epoxy, it should be there somewhere and might be interesting as well to compare all 3 glues.

Durability, u.v., hot and cold resistance as well as life span and flexibility might be interesting as well. Resorcinol has a very long life. They claim the poly's do to.
I am a fan of P.L.Premium- $3. a tube, this might shed more light on the subject.

[ 01-31-2005, 06:04 PM: Message edited by: RonW ]

[RonW]

I read through this several times and had to think about it before some interesting facts finally appeared. And I was a bit surprised.

Think we all can agree that resorcinol is our strongest wood glue, dry or wet, maybe not the easiest or most desirable to use in all situations, but still the strongest. That is why they used resorcinol as a comparison for polyurethane glues.

They used 2 woods, yellow birch and douglas fir.
On the d.f. in the dry test, the polyurethane had a sheer strength of 1200, while resorcinol had 900 lbs of sheer strength, poly had almost a 100% wood failure. In both cases more then resorcinol.

In the next 3 tests which all are wet tests including a boil test, it appears that poly falls way behind resorcinol. Resorcinol has about 2 times as much wood failure in d.f. and almost 4 times as much in yellow birch as does the poly.
Sounds convincing for the resorcinol, But hold it. Look at the sheer strength in the same tests, and this is where it gets interesting.

The poly failed at only about 10% less sheer strength then did the resorcinol.
So it would appear that poly is stronger then resorcinol in dry wood joints and about 90% as strong as resorcinol under wet wood conditions.
After all isn't the real test of a glue joint the actual lbs of sheer strength that it actually takes to rip the joint apart.

As for the greater difference in wood failure in wet wood for the resorcinol.When you think about it, resorcinol requires tight fits and tight clamping, and results in a 5 or 6 thousands glue line. Poly would have a 25 thousands glue line or about 5 times thicker glue line.It would be much easier for the glue line to fail with a much thicker glue line, but again bottom line is - what is the actual sheer strength to pull apart the glue line, and poly only has about 10% less strength then resorcinol in wet woods.

It would make sense that you use metal fasteners as well in wet conditions.

I looked in this site but, as of yet have not found a test comparing epoxy, it should be there somewhere and might be interesting as well to compare all 3 glues.

Durability, u.v., hot and cold resistance as well as life span and flexibility might be interesting as well. Resorcinol has a very long life. They claim the poly's do to.
I am a fan of P.L.Premium- $3. a tube, this might shed more light on the subject.

[ 01-31-2005, 06:04 PM: Message edited by: RonW ]

[RonW]

I read through this several times and had to think about it before some interesting facts finally appeared. And I was a bit surprised.

Think we all can agree that resorcinol is our strongest wood glue, dry or wet, maybe not the easiest or most desirable to use in all situations, but still the strongest. That is why they used resorcinol as a comparison for polyurethane glues.

They used 2 woods, yellow birch and douglas fir.
On the d.f. in the dry test, the polyurethane had a sheer strength of 1200, while resorcinol had 900 lbs of sheer strength, poly had almost a 100% wood failure. In both cases more then resorcinol.

In the next 3 tests which all are wet tests including a boil test, it appears that poly falls way behind resorcinol. Resorcinol has about 2 times as much wood failure in d.f. and almost 4 times as much in yellow birch as does the poly.
Sounds convincing for the resorcinol, But hold it. Look at the sheer strength in the same tests, and this is where it gets interesting.

The poly failed at only about 10% less sheer strength then did the resorcinol.
So it would appear that poly is stronger then resorcinol in dry wood joints and about 90% as strong as resorcinol under wet wood conditions.
After all isn't the real test of a glue joint the actual lbs of sheer strength that it actually takes to rip the joint apart.

As for the greater difference in wood failure in wet wood for the resorcinol.When you think about it, resorcinol requires tight fits and tight clamping, and results in a 5 or 6 thousands glue line. Poly would have a 25 thousands glue line or about 5 times thicker glue line.It would be much easier for the glue line to fail with a much thicker glue line, but again bottom line is - what is the actual sheer strength to pull apart the glue line, and poly only has about 10% less strength then resorcinol in wet woods.

It would make sense that you use metal fasteners as well in wet conditions.

I looked in this site but, as of yet have not found a test comparing epoxy, it should be there somewhere and might be interesting as well to compare all 3 glues.

Durability, u.v., hot and cold resistance as well as life span and flexibility might be interesting as well. Resorcinol has a very long life. They claim the poly's do to.
I am a fan of P.L.Premium- $3. a tube, this might shed more light on the subject.

[ 01-31-2005, 06:04 PM: Message edited by: RonW ]

[Bruce Hooke]

Ron,

You raise some interesting points but I think you are overlooking a couple of things:

1. The section on delamination suggests that poly is much more likely to delaminate under wet-dry cycling. Such wet-dry cycling is, of course, very common in boats.

2. In the tests I presume they used simple edge joints and that the glueline thickness was about the same for the various samples, rather than being thicker for poly.

3. I don't think you are correct in saying that metal fastenings would usually be used in wet situations. After all, this mast will almost certainly not have metal fastenings all over the place. More to the point (since a mast might not really be a wet situation in many cases), one of the most common uses for glue in marine situations is for laminating frames, stems, keels and other parts. In non-monocoque hulls especially, these parts may well have some fasteners in them (such as planking screws), but potentially not enough fastenings to fully hold them together. Even if there are enough, if they delaminate but don't disassemble that would still be highly undesirable. In a non-monocoque hull these parts are also very likely to see the regular wet-dry cycling that caused problems with the polyurethanes.

[Bruce Hooke]

Ron,

You raise some interesting points but I think you are overlooking a couple of things:

1. The section on delamination suggests that poly is much more likely to delaminate under wet-dry cycling. Such wet-dry cycling is, of course, very common in boats.

2. In the tests I presume they used simple edge joints and that the glueline thickness was about the same for the various samples, rather than being thicker for poly.

3. I don't think you are correct in saying that metal fastenings would usually be used in wet situations. After all, this mast will almost certainly not have metal fastenings all over the place. More to the point (since a mast might not really be a wet situation in many cases), one of the most common uses for glue in marine situations is for laminating frames, stems, keels and other parts. In non-monocoque hulls especially, these parts may well have some fasteners in them (such as planking screws), but potentially not enough fastenings to fully hold them together. Even if there are enough, if they delaminate but don't disassemble that would still be highly undesirable. In a non-monocoque hull these parts are also very likely to see the regular wet-dry cycling that caused problems with the polyurethanes.

[Bruce Hooke]

Ron,

You raise some interesting points but I think you are overlooking a couple of things:

1. The section on delamination suggests that poly is much more likely to delaminate under wet-dry cycling. Such wet-dry cycling is, of course, very common in boats.

2. In the tests I presume they used simple edge joints and that the glueline thickness was about the same for the various samples, rather than being thicker for poly.

3. I don't think you are correct in saying that metal fastenings would usually be used in wet situations. After all, this mast will almost certainly not have metal fastenings all over the place. More to the point (since a mast might not really be a wet situation in many cases), one of the most common uses for glue in marine situations is for laminating frames, stems, keels and other parts. In non-monocoque hulls especially, these parts may well have some fasteners in them (such as planking screws), but potentially not enough fastenings to fully hold them together. Even if there are enough, if they delaminate but don't disassemble that would still be highly undesirable. In a non-monocoque hull these parts are also very likely to see the regular wet-dry cycling that caused problems with the polyurethanes.

[Bob Smalser]

Here's what I got out of the USDA poly test:

1) Poly is as good as any glue in dry shear.

2) Poly varies considerably by brand in wet shear and none of it equals resorcinol.

3) Varied performance again in two-cycle boil test, again not near the equal of resorcinol.

4) Very poor performance compared to resorcinol in the more severe cyclic delam test required of Glulam beams.

5) Poly passes the static load deformation standard.

6) There is a primer that improves lamination performance of poly dramatically...if you can find it.

[Bob Smalser]

Here's what I got out of the USDA poly test:

1) Poly is as good as any glue in dry shear.

2) Poly varies considerably by brand in wet shear and none of it equals resorcinol.

3) Varied performance again in two-cycle boil test, again not near the equal of resorcinol.

4) Very poor performance compared to resorcinol in the more severe cyclic delam test required of Glulam beams.

5) Poly passes the static load deformation standard.

6) There is a primer that improves lamination performance of poly dramatically...if you can find it.

[Bob Smalser]

Here's what I got out of the USDA poly test:

1) Poly is as good as any glue in dry shear.

2) Poly varies considerably by brand in wet shear and none of it equals resorcinol.

3) Varied performance again in two-cycle boil test, again not near the equal of resorcinol.

4) Very poor performance compared to resorcinol in the more severe cyclic delam test required of Glulam beams.

5) Poly passes the static load deformation standard.

6) There is a primer that improves lamination performance of poly dramatically...if you can find it.

[sgunns]

Thanks everyone for your comments. As in most of the wooden boat game, there are just as many questions raised in the rersponses. I am having the masts professionally made, however I wanted to check on what the builder proposes. I will let you know our answer in due course. I am still waiting for the price, for an 85 ft x 10 inch, a 65 ft x 6 inch, and two hollow booms.

Steve

[sgunns]

Thanks everyone for your comments. As in most of the wooden boat game, there are just as many questions raised in the rersponses. I am having the masts professionally made, however I wanted to check on what the builder proposes. I will let you know our answer in due course. I am still waiting for the price, for an 85 ft x 10 inch, a 65 ft x 6 inch, and two hollow booms.

Steve

[sgunns]

Thanks everyone for your comments. As in most of the wooden boat game, there are just as many questions raised in the rersponses. I am having the masts professionally made, however I wanted to check on what the builder proposes. I will let you know our answer in due course. I am still waiting for the price, for an 85 ft x 10 inch, a 65 ft x 6 inch, and two hollow booms.

Steve

[Gary E]

Who built the masts for Cris Columbus?
Hire his successors.

The more we debate the advantages of the so called "new and improved", the more I like old.

[Gary E]

Who built the masts for Cris Columbus?
Hire his successors.

The more we debate the advantages of the so called "new and improved", the more I like old.

[Gary E]

Who built the masts for Cris Columbus?
Hire his successors.

The more we debate the advantages of the so called "new and improved", the more I like old.