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Make a Pair of Bunk Glides for Your Boat Trailer

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Picture of Make a Pair of Bunk Glides for Your Boat Trailer
Trying to launch my 18' boat has always been a strain. It would be easier if my trailer had rollers, which it doesn't - it has carpeted bunks. It's all I can do to push the 1400 pound boat and motor combination, especially when I'm perched on top of the trailer tongue, trying to keep my feet dry.

Then again, I have heard several people talk about the potential corrosion my boat can incur from the aluminum hull sitting on carpet, wet with salt water and wrapped around pressure treated wood. I haven't seen any damage, but the boat is new and I'm not crazy about the idea of it happening.

I looked at several different bunk glide products, but realized I would have around 100 bucks in it by the time I was done. There had to be a better, and cheaper, idea. One I could build instead of buy.

Step 1: PVC is Slippery

Picture of PVC is Slippery
PVC may not be quite as slippery as nylon, but while looking at a piece of 1x4" PVC trim board, it occurred to me that it would still make a good bunk glide: it is easy to work, thick enough to countersink the screw heads, and best of all, would provide little friction when I was either launching or pulling the boat out of the water.

I bought a piece of the trim board and twenty 1 1/2" stainless steel screws at my local building supply yard. That's all I needed, and at $30 dollars, it was considerably cheaper than any commercially made bunk glides I had seen.

The piece of PVC trim I bought was 18' long and the bunks on my trailer are about 7' each, so first I cut it to length. Then I cut a slight bevel on the front end of the pieces and lopped the top corner off the rear ends. I then sanded both cuts, making the rear into a rounded bullnose. I also planed and sanded down both top sides for the length of the boards so there were no sharp corners in contact with the hull of my boat.

The photo shows the trim piece after the cut but before finishing the rounding.
 
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tothebin24 days ago

It's a great idea, but be careful. I'm a manufacturing engineer and work with plastics all the time. Plastic glides are great, I have used them on all my boats, including my 22' Starcraft aluminum boat. PVC is easy to work, cheap, and strong. But it can be brittle, oxidizes badly in the sun, and is very abrasive. Watch for cracks, if it breaks the screws you used will damage your hull. Plastic or composite decking boards often have embedded minerals, which would act like fine sandpaper. Instead of buying pre-made nylon boat glides, I go to the local shops that make Starboard (or equivalent) boat accessories and ask the for waste cuttings. The will usually sell them cheap, since a 3" wide strip will make your bunk slider, but is too narrow for almost anything else. I have found 1/2" thick pieces, 8' long and 4" wide, for under $20. Starboard is basically polyethylene, so it's slick, waterproof, and not brittle. One last note, the most common aluminum is 6061, which will quickly turn to white powder in salt water. But almost all aluminum boats are made from 5000 series, which is impervious, as my 1979 Starcraft can attest to. You don't need to worry about salt water in your bunks if your boat is 5000 series (the Starcraft is 5086). What also kills aluminum boats is copper or brass, it actively eats aluminum. Don't use brass screws or copper based anti-sieze in contact with aluminum, use stainless steel. Replace popped rivets with stainless screws or rivets. Also old screws or nuts laying in the bilge will vibrate when running and quickly wear a hole in the soft aluminum bottom.

RangerJ (author)  tothebin24 days ago

Thanks. That's a lot of good info.

The PVC I used for the glides is made for trim on houses. I looked at it today, and it is still looking good; it may contain additives to ensure that it lasts a long time. It is still slick, too, and I can still crank the 18 foot boat'motor up with one hand.

You are right about the screws, and if I see they are getting close to the hull, I will replace the whole works.

I have also heard of people using PVC fence sections with good results. I almost did that, but it is much thinner and lacks depth to countersink the screws. I have used composite materials for other things and found them to be full of all kinds of nasty stuff, like metal. It was weird to be cutting a piece of what I thought was plastic and see sparks shooting off the blade.

I bought a good quality boat, so the aluminum should be ok. Everything is welded, so no rivets or screws in the hull.

Thanks again. That's what I really like about Instructables: the chance to connect with people who know what they are talking about. I see you just signed up; congratulations, welcome, and I am looking forward to your projects.

dsgreene711 year ago
Looks really good. I bet one could also use composite decking boards as well. They have quite a few colors available and maybe use the "hidden fastener" hardware to not worry about screw heads gouging the hull?
RangerJ (author)  dsgreene711 year ago
I would think you could use decking boards, too. Good idea.
tshop1 year ago
That looks great and really economical. Your boat is aluminum, do you think it would work just as well on fiberglass?
RangerJ (author)  tshop1 year ago
Thanks.

I think it would be worth a try. I don't think it would hurt anything, as the PVC is probably softer than the fiberglass. They sell the nylon glides, which as far as I know can be used on glass boats, so I would think this would be ok, too.

The thing is to keep an eye on them - you don't want the screws to work loose and gouge up your boat. I'd also keep an eye on the boat. And, if you have antifouling paint on it, it will probably wear that off and make a mess of the glides, too.
Very nice. Those bunk boards look really professional.
RangerJ (author)  SpringRobin1 year ago
Thanks. I guess it's the white against the charcoal carpet. I've been very pleased with them; they make the launching and recovery so much easier.
Nice job on those! Great use of a lower cost material.
RangerJ (author)  mnflyfisherman1 year ago
Thanks!