Polymer type and Installation

[papdavis]

Hi all,
My buddy and I have a 16X8 fiberglass Dixie airboat. Years ago, when we were strong and poor, we put white polymer 3/8 sheets on the bottom of the boat using 1/4 " flathead screws, countersinked. I don't remember the year we did this, but it's now cracking due to age. (maybe 1990s)

I have looked at this site for info...still confused but have questions...

We are not poor, but no longer strong due to age...but we want to do this project by ourselves, reliving past triumphs!

So, the questions are:
1. What type of polymer to use? Red, blue, white?? Still 3/8"?

2. Where is the best place to purchase the best polymer- we live in Houston, Texas.

2. Since we have through bolted the old polymer, should we continue to use the flathead screws , countersinked? Or is there a better type of bolting?

Thanks to all for your help!

Don

 

[Slidin Gator]

White does not have any UV stabilizer, typically no other additives. Get 3/8 UV stabilized in whatever color you like, black is the most available right now and availability is the key right now. If you can't find UHMW sheet in Houston, you can't find it anywhere right now.

I prefer riveted, but you already have the holes for screws, stick with that. Lay the boat upside down in the hot summer Houston sun, lay out the sheet and hang weights off the sides with vise grips to keep it tight. Start drilling and screwing from the middle of the transom and work your way out and forward. Only work in the heat, UHMW expands a lot when hot and will be tight as a banjo string in the water. Don't try to pre-drill, just do one hole at a time. Absolutely countersink the flat heads, one at a time.

If you want to go full in old guy anal, add SST sealing washers on the inside.

McMaster-Carr

 

[JLP3314]

Always wondered how to do it, (I had DB replace it on my aluminum hull).
Thanks Slidin' Gator!

 

[Slidin Gator]

The key is to get it hotter during installation than it will get in service. If it heats up beyond the installation temperature, it grows larger than the screw restraints and start to bubble off the hull, creating much more drag. It's not so much of an issue for a hull seeing water, but put that hull on the bone dry ground in sticky grass/mud on a hot afternoon and it doesn't take too long before the poly is smoking hot and you run out of accelerator.

Think about an open hull vs. deckover in the hot sun, that open hull is baking the poly all day while the deckover keeps the hull shaded. White paint on the inside of an open hull runs cooler than black.

 

[papdavis]

The key is to get it hotter during installation than it will get in service. If it heats up beyond the installation temperature, it grows larger than the screw restraints and start to bubble off the hull, creating much more drag. It's not so much of an issue for a hull seeing water, but put that hull on the bone dry ground in sticky grass/mud on a hot afternoon and it doesn't take too long before the poly is smoking hot and you run out of accelerator.

Think about an open hull vs. deckover in the hot sun, that open hull is baking the poly all day while the deckover keeps the hull shaded. White paint on the inside of an open hull runs cooler than black.

Yes sir, Thanks for your explanation! Great to have an expert to explain the science!

 

[blinker]

Hi all,
My buddy and I have a 16X8 fiberglass Dixie airboat. Years ago, when we were strong and poor, we put white polymer 3/8 sheets on the bottom of the boat using 1/4 " flathead screws, countersinked. I don't remember the year we did this, but it's now cracking due to age. (maybe 1990s)

I have looked at this site for info...still confused but have questions...

We are not poor, but no longer strong due to age...but we want to do this project by ourselves, reliving past triumphs!

So, the questions are:
1. What type of polymer to use? Red, blue, white?? Still 3/8"?

2. Where is the best place to purchase the best polymer- we live in Houston, Texas.

2. Since we have through bolted the old polymer, should we continue to use the flathead screws , countersinked? Or is there a better type of bolting?

Thanks to all for your help!

Don

Check out my Bondable UHMW polymer called OceaPoly. It last 4 times longer than mechanical fastened HDPE polymer according to the US Coast Guard. No fasteners no holes, no expansion or contraction. For more information go to www.oceapoly.com

 

[OneBFC]

Check out my Bondable UHMW polymer called OceaPoly. It last 4 times longer than mechanical fastened HDPE polymer according to the US Coast Guard. No fasteners no holes, no expansion or contraction. For more information go to www.oceapoly.com

Well, let's get one thing cleared up for everyone here.

Almost no one uses HDPE on their airboat to begin with. High Density polyethylene.

What everyone uses is UHMWPE. Ultra High Molecular Weight Polyethylene.

So, while your product may be quite nice, it will in no way last 4x as long as what is typically used by everyone.

No reason to try and be deceptive and rely on the ignorance of people here. You generally won't get away with it here anyway given the experienced old farts we have...wait, guess I am getting old too. Anyway....

Bonded installs have been tried here before and some have had success and others not. Oceapoly isn't a new product on the global market and wasn't developed for airboat use. What's unique to airboat use is that it will get very hot vs when used on a real boat like it is typically used for. That heat really stresses the adhesive and if it delaminates its a bad day for the boat owner for sure....

So, while very attractive to not have to drill holes in our ever more expensive hulls, you have a pretty steep trust hill to climb reliability and safety wise.

I wish you all the best in making it work and we will have an alternate to a thousand rivets....