Screws vs. Ring Nails

Randy,
When I was picking up my 16 foot kit, I believe you expressed a preference for ring nails over screws in the chine log because of greater ingress of water and rotting if screws are used. I am about to put on the UHMW plastic bottom. The instructions I have call for screws to attach it. Unlike the other fasteners going into the chine log, fasteners securing the plastic bottom cannot be sealed away from water with anything. Is there any experience securing the plastic bottom with ring nails? I would be very interested in your comments or the experience or perspective of any of the members.

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Permalink Reply by Randy Dersham on February 6, 2009 at 7:33pm
I'm glad the boat is coming along so quickly. Congratulations.
The UHMW plastic expands and contracts a large amount. It is also impossible to glue to the bottom of the boat so it is very important to be able to remove it at the first sign of any trouble.

Use screws only. Mark and cut the UHMW to it's final fit when your work space is near 65 to 70 deg. The temperature is important because it is the mid range of how large or small the bottom might expand or contract. We use a dab of 3M 5200 on each screw. Greg Hatten used Bee's Wax and we had a little discussion about that last month. Here's the link to that thread so you don't have to search the forums. http://www.woodenboatpeople.com/forum/topics/bees-wax
Permalink Reply by Daniel Paull on February 11, 2009 at 3:12pm
Hi Randy,
Well, I followed your instructions and screwed the UHMW plastic bottom on. I put 70 screws dabbed in 5200 around the perimeter into the chine logs and frame number 9. I was about to start putting screws into the other frames when it occurred to me that it might not be necessary. If the plastic comes off, it will start at the perimeter, and there is no seal between it and the plywood bottom. Are you aware of anyone else who has done it this way? I can always flip the boat back over and add those screws, but for the moment I plan to go without them. I've added some pictures of the nearly completed boat which mimics Robb Sipler's boat which really caught my eye. My son and I plan to hurt (but not kill) some Skykomish steelhead this weekend. Even with the many mistakes I made putting the boat together, we think she is beautiful, the materials you provided were first rate, and my son and I had a fine time with the project. Thank you and Sanderson very much for all your help.
Dan Paull
Permalink Reply by Randy Dersham on February 11, 2009 at 4:28pm
Great job on the boat Daniel. It looks super.
I think you two have been at it about five weeks from pick up at the shop to putting your boat on the water. Is that about right?

Yes we have seen UHMW attached with fewer screws than the traditional every three or four inches. None quite as few as you are talking about.

The material is heavy enough that the perimeter method that you are using might put some extra tension on the edges when the bottom is not supported.. Obviously that would only happen for very short periods of time while loading or unloading. You will have no trouble at all as long as the material is new. As it ages and begins to get brittle you might get a few years less performance from the bottom.
Permalink Reply by Kurt N. Sallaz on May 6, 2009 at 1:27pm
Hi everybody,
I realize I'm getting in on this conversation late in the game but I wanted to put my 2 cents in for future reference for anybody that wants to use UHMW for boat bottoms. I work for a company that has a fiberglass backed UHMW product called OceaPoly (tm) that can be bonded to hulls made of wood, fiberglass, steal or aluminum, even concrete using a two part epoxy. It can even be welded with an extrusion welder at the seams. The unfortunate part is that my company isn't set up to sell to private parties. For that, we have to do the installs "in house" as it requires special tools and processes.
Another aspect of UHMW is bio films can't stick to it so boats that are moored don't need scraping. So any way that's my 2 cents worth.
Permalink Reply by Jason Knight on May 7, 2009 at 7:01am
Kurt,
There is a builder here in MI who was showing me a UHMW product that sounds like what you are talking about. They were bonding to the bottom of their boats which were made of plascore... The one side was all slick like normal, and the backside had a toothy texture to it... same stuff?
Permalink Reply by Kurt N. Sallaz on May 7, 2009 at 7:19am
Hi Jason,

No, I don't believe it to be the same thing. Our product has fiberglass fabric on one side. I know there are various types out there but I don't know how well they perform. The stuff you describe sounds like it is designed to increase bonding surface area. The problem I see with that is it is still UHMW and the whole prupose of UHMW is nothing sticks to it so eventually the bonding agent will let loose of the UHMW. I can tell you that our OceaPoly is patented.
Permalink Reply by Jason Knight on May 7, 2009 at 7:40am
Hmmm, I wonder material they use for the back side then...

Quote from website:
"All of our boats motor extremely well because we have not been stuck in traditional boat designs that draw lots of water and are made for white water conditions. For a small upgrade you can get the U.H.M.W. bottom which is ground breaking no fastener system that allows a very slick bottom on your boat that will take a ton of punishment. We also use a strong truck bed liner in the floor of the boat and on the side chines to protect from wondering logs and rocks you may come up against on your river adventure."
Permalink Reply by Kurt N. Sallaz on May 7, 2009 at 5:55pm
If you can send me a link to this web site I may be able to shed more light on their product.
Some companies offer double stick tape to adhere their sheets with, some have a product with fiberglass threads in it which work only for a short while because there are so few threads in it, some have an etching method to which you actually chemically melt it to get it to stick to it self in the case of seaming. To be honest- I'm not fully aware of the other methods out there.
Permalink Reply by Jason Knight on May 8, 2009 at 6:00am
Kurt,
Here is the link to the site - not sure if they fully explain the material, but take a look.

www.stealthcraftboats.com
Permalink Reply by Kurt N. Sallaz on May 9, 2009 at 5:43am
Mornig Jason,
I looked at the site but he really dosen't say how they attach UHMW to the bottom of their boats. They sound like real nice boats though. We have done boats in our shop but we aren't set up as an installation facility. We also go out to do installs. We are working to make it more user friendly. I did a toy boat for taking to shows which I attach to this. Sorry, the first picture is upside down and I couldn't seem to delete it the second is the same but right side up.
Attachments:
Permalink Reply by Randy Dersham on May 10, 2009 at 11:51am
Hello Kurt.
Your email prompted me to drop a line to your company. I like very much the ability you have to weld seams and am interested in the 1/8 in product for our boat bottoms. I've received a phone call from the company and went over some of the details. We already have the ability to vacuum bag. The only drawback is the cost. It looks like I would have to charge about $1,200 for a boat bottom installed. I'd love to find out that I'm doing the calculations wrong.

That is almost four times the cost of someone screwing down their own 1/4 sheet of UHMW and double the cost of us doing a bottom fix and new UHWM install; however, some people might still go for it. I think I would be able to fair amount of these if I could manage the price.
Permalink Reply by Jason Knight on February 7, 2009 at 5:13am
Ring nails are great - but man they are easy to bend when hammering them in... haha.
Had to add that!
-jk-

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