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PostPosted: Thu Feb 27, 2014 6:40 am 
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I hate the sound of plastic rubbing against concrete boat ramps. Last year, just after launching on a concrete boat ramp to go for a night fishing trip, a storm blew up and proceeded to bang the crap out of my keel on the boat ramp. After that, I started searching for a way to prevent that deep cringe from permeating my face yet again.

There are a few commercial solutions available which look very good, but were also too expensive for something that should be considered sacrificial in my opinion.

Then there are the folks who go for JB Weld to build up the high wear areas and simply re-apply when it gets warn thin.

I found a post where someone decided to use Gorilla tape as his keel guard, but that seemed too thin of a layer to really protect against damage.

Being that I do a lot of triathlons and have put too many miles on a bicycle while wearing spandex than I plan to remember, one day while replacing a road bike tire, I realized I had a durable rubber which would be perfect as a sacrificial keel guard for the hard plastic kayak, but the issue was attachment. I cut the beads of the side wall off of the tire (the beads are what hold the tire onto the rim for a 'clincher' style tire) and tried marine goop... bad idea. Then I took the idea of Gorilla tape and laid my sliced up tire within the boundaries of the tape, and applied it to the keel of my Pro Angler (at the time, the boat I had) from the stem all the way back to the beginning of the mirage drive well. That keel guard stayed there until I sold the boat two weeks ago. That horrific sound of the plastic being 'sanded' by the concrete ramps was abated.

This past weekend, I did the same sort of keel guard on my new Adventure and my wife's Revolution and actually took a few pictures. I did use a narrower strip of Gorilla tape this time around, but I don't anticipate any problems with the lesser sticky surface area. Also, I put an additional angled strip around the curvature of the stem as the tire doesn't like to make that curve. I am positive there is a little additional resistance in the water with my keel guard solution, but the slight increase in hull friction I find made up for with piece of mind knowing I can beach the boats without slowly eating my hull

Any bike shop would have some old tires laying around. It doesn't matter if they are filled with holes or even if they had a blow-out. You only need a few good feet of tire and you can have a keel guard that might just last you a lifetime with a few replacement layers of tape.

On to the DIY Tramps... I was not ready to spend nearly $400 on them, but wanted to try them out, so I put on my Google hat and went to work. I wanted my nephew and niece to be able to come out into the world and play on their uncle's sailboat, so I went with the traditional, fabric tramps. I thought about going with the super cheap blue tarp version, but decided against it. What I decided on was trampoline material sold by Fun Spot Trampolines. They were the least expensive for the amount of material. They have them ~160" wide with a minimum order of 3 yards... so I have a ton of the material for under $60 (enough for three Adventure Islands). My wife has a sewing machine, we bought nylon thread, a canvas needle, 10 buckles, and some nylon strapping and went to town. The design is very similar to the Hobie tramps with the notable exception being that the rear bar at of the tramp going to the rear Aka is a piece of 1/2" CPVC pipe. It is considerably lighter than it's galvanized counterpart, and with the load distributed across the bar, really does not have any obvious disadvantages for my purposes... Up next is the splash guard and then perhaps a rear platform for additional cargo on calm days? I only have nearly 2 yards of tramp material left!

[img][IMG]http://i1294.photobucket.com/albums/b601/nethomp6/Mobile%2BUploads/image_zpsd5969ed7.jpg[/img][/img]
[img][IMG]http://i1294.photobucket.com/albums/b601/nethomp6/Mobile%2BUploads/image_zps9926bb7b.jpg[/img][/img]
[img][IMG]http://i1294.photobucket.com/albums/b601/nethomp6/Mobile%2BUploads/image_zps10c4f199.jpg[/img][/img]
[img][IMG]http://i1294.photobucket.com/albums/b601/nethomp6/Mobile%2BUploads/image_zps1d9cbdcf.jpg[/img][/img]
[img][IMG]http://i1294.photobucket.com/albums/b601/nethomp6/Mobile%2BUploads/image_zps1d9cbdcf.jpg[/img][/img]
[img][IMG]http://i1294.photobucket.com/albums/b601/nethomp6/Mobile%2BUploads/image_zps67d7bda5.jpg[/img][/img]


Last edited by pintailchaser on Thu Feb 27, 2014 1:39 pm, edited 2 times in total.

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PostPosted: Thu Feb 27, 2014 10:00 am 
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Location: North Central Arkansas
Could you post some photo's of your Keel guard.


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PostPosted: Thu Feb 27, 2014 10:21 am 
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I do somewhat similar, but with different materials. I put a thin coat of West Systems G-Flex on the prepared area (light sand, wash with alcohol then flamed) to guaranty a permanent bond. I then mix enough two-part epoxy putty to form a new thicker sacrificial keel, 3-5" long. I haven't worn through one yet.

Great idea with the bike tire.

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PostPosted: Thu Feb 27, 2014 10:41 am 
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Done and done! The first post should have the links to photos now.


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PostPosted: Thu Feb 27, 2014 3:28 pm 
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Location: Kailua 96734
I've used RED gorilla tape along the bottom of my AI for some time. It's not permanent but absorbs many dings and scratches. Easy to reapply.

The commercial keel guard products I tried won't adhere well to the curved keel areas.


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PostPosted: Thu Feb 27, 2014 5:53 pm 
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I bet that red tape looks good on the hull! It probably fits the contour of the hull much better as well. My take tends to be on the 'overkill' side of design, and it would probably work just fine with the tape and without the bike tire, but I do like the added mental security the padding gives me. Did you just do the bow, or also the stern skeg area?


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PostPosted: Fri Feb 28, 2014 12:09 am 
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Location: Kailua 96734
Stem to stern. Down the middle. Blends right in.

Unfortunately, the pop up reefs around here don't always aim at the centerline. :lol:


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PostPosted: Fri Feb 28, 2014 5:12 am 
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NOHUHU wrote:
Stem to stern. Down the middle. Blends right in.

Unfortunately, the pop up reefs around here don't always aim at the centerline. :lol:



Dagnabitt those asymetrical reefs!


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PostPosted: Fri Feb 28, 2014 7:18 am 
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Location: Sarasota,Key West FL
pintailchaser :
I'm on my third TI now, we use the heck out of our Hobies and I used to worry about scratching the bottom and would be very careful at concrete ramps and beaching in fear that I was going to ruin the bottom or worse yet wear thru the bottom of the keel. I gave up on worrying about it after a while, realizing along that keel the material is about 3/8 of an inch thick and it would take literally years of severe abuse to wear thru it, of course if you were to lift the bow and drag the rear across a concrete parking lot with no scupper cart, that would be a different story (LOL).

Basically the bottoms of all my Hobies look like crap after a while, I just don't worry about it. Of course Hobie sells a plastic welder kit with color matching welding rod that really works well for repairing those scratches and grooves from oyster beds and sharp rocks. You can also use the hot iron tool to smooth out scratched up areas (kind of liking ironing a shirt), I think the welder kit is around $60 bucks, and definitely a must have tool for Hobie owners ( I've had 7 Hobies now, and have welded or repaired all of them at least once). It's time consuming and something you really don't need to do very often. I'll get a bug about once a year and decide I want to clean up the bottom, it takes about half a day to make it all pristine again. If you want to remove minor scratches I found it best to take a sharp single edge razer blade or exacto knife standing straight up and rubbing back and forth sideways (not lengthways of the blade), it peels the top layer and smooths it out very quickly leaving a nice smooth finish. I used to own a stereo lithography prototype manufacturing shop, and that's the method we use to scrape the lines from the build layers out of the plastic parts. This is typically what I do on the bottom of my hull annually, I repair the really deep scratches with the welder first of course, then just scrape everything smooth. It would literally take years and years of scraping to scrape thru the bottom of the hull.
Of course I'm careful on concrete boat ramps and always stop before getting to the ramp, get out then lift the front of the kayak onto the ramp, basically it's not a very good idea to pedal like crazy as you approach the ramp, then let the boat beach itself onto the ramp, that would wreck any boat (even fiberglass, or aluminum), basically just don't ever do that. if you spend a couple hrs at the ramp you will notice no powerboater who knows what they are doing would ever do anything like that either. They typically pull up to the dock (in deeper water) unload their boat, then pull their trailer down into the water, then drive the boat up on the trailer, the boat itself never ever touches the shore. Same goes with beaching, I don't know too many that would actually allow their power boat to drive up onto the sand (like on a sand bar), too much risk unless the bottom is really soft fine sand like here in florida. What most powerboaters do is anchor just off shore then walk to shore in knee deep water especially if they don't want to get stranded if the tide goes out (that happens a lot LOL)
Actually I usually put my scupper cart wheels under the cart in waist deep water then roll the boat up the ramp, it's a lot easier to me to put the wheels under the cart in the water then just roll it out of the water vs trying to lift the darn boat to put the wheels under once on dry land.
Oyster beds are the worst, I try to avoid them if possible.
Hope this helps
Bob


PS: This is just an idea and something that I have not actually tried, and probably won't, but here it goes.
If you look under the hood of your car you will see a white plastic reservoir filled with anti-freeze (pretty much all cars have them now), this is called a pressurized cooling vessel system, and is designed to withstand 20 PSI of internal pressure (we called it the living lung when developing it originally, first for Mercedes in Europe, then Chrysler in the US) because it expands like a lung under pressure. I headed the teams that developed them originally, those are made from very similar plastic to Hobies boats, they are made in two halfs then hot plate welded together (I've probably designed and built 300+ molds for these crazy reservoirs all shapes and sizes). The point being it might be possible to use a variation of hot plate welding to add a keel protector to the bottom of your keel. Plastic is a very poor heat conductor so you can use this to your advantage. What you would need is some polyethylene plastic (example... cheap kitchen cutting board material from Walmart). Cut the cutting board into blocks so they look like the tiles on the bottom of the space shuttle. I would think a bunch of 1" by 1" sq blocks placed down the center of the of the entire hull 2 rows wide would work well. You will need a precise temperature controlled heat source like an induction cooktop, a good quality Teflon fry pan (that new ceramic Teflon type coating works best). You will need a flat bottom tool of some sort like the end of a 1" rod polished flat and smooth and some super glue. Basically what you do is glue each rectangular block onto the end of the holding tool, then place the block into the frying pan (at 450F deg (experiment to get the best temp)) until the bottom of the block is totally molten on the bottom, since plastic is a poor heat conductor this is actually pretty easy and fast (of course if you leave it in to long it turns into what looks like a pancake or a fried egg ( LOL)). Of course you will have the bottom of the boat all laid out with grid lines. Basically you just one at a time take each hot block and press them into place on the bottom of the hull (exactly the same way they do the bottom of the space shuttle). You can probably do the whole 2 inch strip the length of the hull in about an hour. Once the plastic solidifies just break the insertion tool off the block by twisting it. Once done then if you take the Hobie welder and fill in all the grooves in between each block with the welder. Once done you can sand down all the blocks smooth with a belt sander so the edges are just above flush, and the center is nicely rounded and smooth. It is impossible to remove the blocks off the boat once installed as the plastic itself is welded to the hull and is now part of the hull. If you make 5 or 6 of those anvil insertion tools it will go a lot faster.
All the heat is localized to just the area of each block and cools down quickly so warping the hull itself would be very unlikely.
If I was dead set on adding some kind of keel protection, this is how I would do it myself, personally I'm not going to bother, it's way faster and easier to just scrape the hull smooth and clean once every year or so.
Of course you can go hog wild and tile the entire bottom of your Hobie so it can survive earth entry from space, but that might be a little much (LOL)


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PostPosted: Wed Apr 02, 2014 9:06 pm 
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Location: Adelaide, South Australia
Your replies are great, so much detail.

I didn't do as you and put the cart in too shallow water and put a hole in the tube, part way up.
I filled with some pipe from bottom to top and borrowed the dealer's welding gun and rod and welded it in. Has lasted over a year but I think the bottom is slightly protruding and has pushed the top up and fractured the floor part way around the tube and 1/4" from it. I could take a photo if needed but I don't like looking at the imperfection :(

Not a big deal as that area isn't under water constantly. I asked about buying the welding gun but the dealer also had to buy a device to convert from our 240v to your 110v. So I am thinking maybe a temp controlled soldering iron (which I have at 240v) with a shoe made by me with the hole in it. This would allow me to do repairs without having to go to the dealer.

I did find if I left the rod in the hole too long it went black so even with the 110v Hobie iron, I had to be careful about over-heating. With your vast experience with plastics, do you know if the temperature would be near enough from a soldering iron?
Cheers,
Brian in South Australia


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PostPosted: Wed Apr 02, 2014 10:08 pm 
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Location: Sarasota,Key West FL
Hdpe melts at around 265f, as long as your heat gun is below 300f you should be fine. Typical solder irons are around 600f which is too hot.
Bob


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PostPosted: Wed Apr 02, 2014 10:29 pm 
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Location: Adelaide, South Australia
Thanks Bob, there seem to be plenty of temperature adjustable soldering irons available in Aus.
I have some 1/4" plate copper which I can shape like a small iron, drill a hole in for the plastic welding rod and braze in a rod to attach to the soldering iron. If I duplicate the size of the Hobie iron, I should be able to keep it near but below 300 F.
Will take a photo and post.
Cheers,
Brian in South Australia.


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