Which wood piece is stronger ? Solid or laminated ?

[Leeward Rail]

I need to build a new wood mast step for our C&C. The original is a rectangular solid piece of oak about 2.5 inches thick which is bolted to the hull.

I have a friend who has the same boat and he made his from 3 pieces of oak, laminated together.
I assume each section waa done with the grain perpendicular to each other.

Which is better ? Solid piece of oak covered in thinned epoxy or 3 thinner pieces of oak epoxied on top of each other ?

I would assume that the thick wood piece is stronger but the laminated one would be more less likely to warp.

The laminated one would be cheaper but in this case I would rather not deal with this ever again.

 

[Tally Ho]

I don’t think it will make much difference…as long as you seal it (either option).

Maybe the composite alternating the grain is better, but solid oak would be pretty strong.

Greg

 

[Leeward Rail]

as long as you seal it

I wish someone had told the 2 previous owners that LOL... They sealed the outside but didn't seal the 2 drainage holes.
(The photo shows the new one my friend made for his boat, with the drain holes both lined and sealed)

If there isn't much difference, I figure will just laminate one. Wood would be easier to buy and as a bonus, likely cheaper.

 

[Benny17441]

The goal should be something that is good enough.

 

[MikeHoncho]

coming from a woodworker… both have equal enough compression strength to be a non issue. The laminated version is more stable if the layer‘s grains are orientated . The solid version looks better unless you alternated hardwood species .

 

[Justin_NSA]

Ash and hickory are stronger than oak. Just FYI

 

[thinwater]

Without knowing the strength requirement, questions like this are always funny. No way of knowing if it is 5 times or 1/5 the required strength.\

a. Base the replacement on the failure mode of the original. Rot after 30 years, but without actual failure? Then the original design was fine, perhaps with better water sealing or better drainage. Did it crack along the grain? Then laminated would be better.

b. Calculate the actual load, look at the properties of materials, and then assign a safety factor".

"Stronger" isn't really the right question. A solid piece is stronger in one direction, and a laminated piece will have more balanced strength across the grain and be less prone to splitting. Obviously?

 

[Leeward Rail]

a. Base the replacement on the failure mode of the original. Rot after 30 years, but without actual failure? Then the original design was fine, perhaps with better water sealing or better drainage.

Yup.

In this case original design was fine other than needing better sealing.

Without knowing the strength requirement, questions like this are always funny. No way of knowing if it is 5 times or 1/5 the required strength.

The oak would apparently meet the requirement. Based on both past history of the previous part, and the reputation of the designers of the boat.

The question isn't if solid oak is good for the job, but if the act of laminating 3 pieces together with epoxy meets the same requirement, without introducing a point of failure.

"Stronger" isn't really the right question. A solid piece is stronger in one direction, and a laminated piece will have more balanced strength across the grain and be less prone to splitting. Obviously?

That may be obvious to you but it may not be to others.

I myself realize that with solid wood, due to factors like grain and moisture content, it can result in 2 different pieces having different stability. Anyone who has done basic woodworking knows that solid wood is prone to cupping, twisting. Whereas laminated wood can reduce that.

In this case...Having never laminated wood with epoxy before, I don't know if the resulting benefit of "balanced strength" has any drawbacks in other ways that come into play here.

 

[Leeward Rail]

The goal should be something that is good enough.

I suspect that is what the engineers at Ford have been saying recently.

"Good enough" is a horrible concept.

If you can improve something, especially without too much increased cost or effort, I believe you should do it.

 

[Leeward Rail]

Ash and hickory are stronger than oak. Just FYI

I contacted a friend of mine who does hardwood flooring and he suggested White Oak, because it was more resistant to moisture and harder than both Ash and Red Oak ?

I am going to seal it much better than the old piece, but extra inherent moisture resistance seems like I good thing, unless white oak is crazy priced compared to red oak or ash. Been a long time since I bought anything but spruce lumber.

 

[Will Gilmore]

I have a friend who has the same boat and he made his from 3 pieces of oak, laminated together.
I assume each section waa done with the grain perpendicular to each other.

As near as I can tell from the photograph, your friend's piece is not laminated with gains crossed. However, his laminated piece would improve the dimensional stability because wood usually grows with internal tensions working against each other. The grain can be interlaced, the rings from one year to the next can stretch or pull on each other, the radial drying across growth rings can cause splitting of cupping, etc. By ripping the planks into thinner strips, these tensions are released. It works best to flip every other piece end for end, if using the same stick of wood to glue back up. The furniture manufacturer I worked for did this with every board that came into the rough mill. Wide board were ripped down to two inch strips and glued back up into table tops or side panels because they were more stable after that process.

It's also cheaper to buy 4/4 stock than 12/4 stock (1" stock vs 3" stock). White oak and ash are better than red oak for resisting rot. I know hickory is very strong, but I don't know it's water resistant properties. I do know it is harder to find and more expensive in my area.

"Good enough" is a horrible concept.

If this is so, then it isn't good enough.
My father always said, "Good enough was perfect."

With new finish and sealing agents today, you are not likely to have any issues for forty or fifty more years, as long as it is completely sealed and the finish remains intact.

-Will

 

[Don S/V ILLusion]

More fundamentally, why use wood of any type where water/moisture is always present? Sealing it is never permanent.

there are a myriad synthetic materials as if not stronger, more permanent and don’t rot or rust.

 

[Leeward Rail]

More fundamentally, why use wood of any type where water/moisture is always present? Sealing it is never permanent.

there are a myriad synthetic materials as if not stronger, more permanent and don’t rot or rust.

I have wondered that myself. There is no reason that C&C couldn't have made it from something else. Maybe they did it due to cost or ease of availability..
In my case it is more familiar to do with my tools and experience and admittedly a bit of just "replace what is there" even though I like improving things when I do projects of any kind.

Getting starboard here is difficult. I wonder if the local plastics company has anything. Aluminium would obviously work as long as you compensated for galvanic corrosion where the fasteners are. In fact C&C likely should have simply made a larger casting instead of the small aluminum pan that sits between the mast and the original oak.

 

[capta]

I have wondered that myself. There is no reason that C&C couldn't have made it from something else. Maybe they did it due to cost or ease of availability..
In my case it is more familiar to do with my tools and experience and admittedly a bit of just "replace what is there" even though I like improving things when I do projects of any kind.

Getting starboard here is difficult. I wonder if the local plastics company has anything. Aluminium would obviously work as long as you compensated for galvanic corrosion where the fasteners are. In fact C&C likely should have simply made a larger casting instead of the small aluminum pan that sits between the mast and the original oak.

I'm with Don on this one. From your original question, I wondered why no one mentioned something synthetic. Perhaps the reason C&C didn't was because nothing was available to fit the bill when your boat was built? Times have changed, as have available materials.

 

[Leeward Rail]

With new finish and sealing agents today, you are not likely to have any issues for forty or fifty more years, as long as it is completely sealed and the finish remains intact.

Would staining the wood adversely alter the adhesion of epoxy used as a sealer ?
Sure would be pretty to have it look closer to the other wood in the cabin.

 

[Leeward Rail]

Found a good reference that talks about bonding white oak with epoxy. I had found some comments online about white oak being problematic with epoxy. Evidently it isn't an issue now, assuming it really ever was.

So Stands the Mighty Oak

What we learn from this data is surface prep can make a difference in epoxy's adhesion to white oak. Choice of epoxy is also important.

www.epoxyworks.com

Here is some older info prior to gflex being developed.

Using Epoxy with Oak

Editor’s Note: This article about epoxy and oak was originally published in early 1995, and is shared at Epoxyworks.com for historical purposes. A dozen years after this article was written, we developed G/flex epoxies, which are rubber toughened to withstand shock, vibration, expansion and...

www.epoxyworks.com

 

[thinwater]

Yup.

In this case original design was fine other than needing better sealing.


The oak would apparently meet the requirement. Based on both past history of the previous part, and the reputation of the designers of the boat.

The question isn't if solid oak is good for the job, but if the act of laminating 3 pieces together with epoxy meets the same requirement, without introducing a point of failure.


That may be obvious to you but it may not be to others.

I myself realize that with solid wood, due to factors like grain and moisture content, it can result in 2 different pieces having different stability. Anyone who has done basic woodworking knows that solid wood is prone to cupping, twisting. Whereas laminated wood can reduce that.

In this case...Having never laminated wood with epoxy before, I don't know if the resulting benefit of "balanced strength" has any drawbacks in other ways that come into play here.

I think the answer is laminating will be more balanced. As lone as the adhesive is stronger than the cross-grain bond (which epoxy is) there is nothing lost in your application. And I think laminated would look very good.

 

[thinwater]

I have wondered that myself. There is no reason that C&C couldn't have made it from something else. Maybe they did it due to cost or ease of availability..
In my case it is more familiar to do with my tools and experience and admittedly a bit of just "replace what is there" even though I like improving things when I do projects of any kind.

Getting starboard here is difficult. I wonder if the local plastics company has anything. Aluminium would obviously work as long as you compensated for galvanic corrosion where the fasteners are. In fact C&C likely should have simply made a larger casting instead of the small aluminum pan that sits between the mast and the original oak.

Starboard is a terrible choice. It will creep under load. Only for non-structural, low-stress, or cosmetic uses. Google Starboard and creep and cracking.

Ash is not used much on boats because of rot.

You would stain it AFTER bonding. No, it won't hurt anything.

I thing oak is a fine idea. It lasted this long. But pre-laminated fiberglass sheets, built up, would be fine too.

 

[MikeHoncho]

Would staining the wood adversely alter the adhesion of epoxy used as a sealer ?
Sure would be pretty to have it look closer to the other wood in the cabin.

Yes, if you want it darker then google "ammonia fuming" sounds bad, it can be but with this small piece it would be easy and look much, much better than any stain. I buy my ammonia from a local hardware store at 12% concentration (only use it outside).

 

[Will Gilmore]

Would staining the wood adversely alter the adhesion of epoxy used as a sealer ?
Sure would be pretty to have it look closer to the other wood in the cabin.

Yes, if you want it darker then google "ammonia fuming" sounds bad, it can be but with this small piece it would be easy and look much, much better than any stain. I buy my ammonia from a local hardware store at 12% concentration (only use it outside).

I don't know the details around stains and epoxies, but there are three basic types of stains: oil-based, alcohol-based, and water-based stains. I would not use oil-based stains as oil takes forever to completely dry. I would look into alcohol-based stains; excellent penetration, not water soluble, and dries thoroughly.

-Will