Bunk boards or rollers?

June 6, 2011 1:16 PM

Boat trailer advice needed!

I need some advice on my boat trailer . . . I have small 1955 aluminum speed boat (16') with an equally ancient 25 hp Johnson and an almost as ancient trailer. Last year, after 50+ years of bouncing down the highway, the boat hull developed a couple stress cracks where it sits on the rollers. Originally, the trailer had four keel rollers, 4 side rollers, and the bow stop. My solution (after a lot of cursing and patching the boat) was to replace the side rollers with bunk boards, which was easily done over the weekend. However, the increased height of the bunk boards means that the hull no longer meets the rear 3 keel rollers, and they don't have enough adjustment to raise them up high enough to do so.

My question is, do I even need keel rollers anymore? The boat is now supported for almost 1/2 of it's length on the bunk boards (basically, more than the length that used to be supported by the now-defunct rollers). After a significant amount of googling, it seems that the interwebs cannot give me a clear answer one way or the other. Anyone out there with experience or advice? Am I courting disaster when I go to tow my boat 450 km to the cottage this weekend?

posted by fimbulvetr to Travel & Transportation (6 answers total)

I think the main issue is when you load the boat back onto the trailer on a shallow launch ramp are the bunk boards sufficiently carpeted to prevent the hull from being damaged as it slides over them? Ideally, the bunk boards and the rollers would share the distributed weight of the boat, so that when the boat is hauled back onto the trailer it isn't sliding its whole weight across the bunks, and instead some of that weight is borne by the rollers. In practice, if you can float the boat onto the bunks while it's in the water, the rollers don't even come into play.

Again, once on the trailer I think the weight of the boat should be shared by both bunks and rollers if at all possible -- the rollers support the boat under the keel, but the bunks help keep the majority of the weight off the rollers so the boat will roll more easily.

FWIW, I have a 13' aluminum boat w/15 hp motor on a trailer with bunk boards and keel rollers. My boat doesn't really touch the keel rollers once the boat is fully on the bunks, but it does touch the forward most roller as it gets loaded back onto the trailer. My boat is fairly light, but I haven't had any issues with this arrangement.
posted by mosk at 1:46 PM on June 6, 2011

Response by poster: My boat is pretty light too. I could easily slide it on the bunk boards when it was dry and level in the driveway, so I'm not too worried about it on a ramp in the water -- it should float most of the way in if the water level at the river is up (should be with all the rain). It does still sit on the forward roller, but it is the back three that are now defunct. I'm more worried about damaging the boat when hauling it than getting it in and out of the water.
posted by fimbulvetr at 1:56 PM on June 6, 2011

I'd definitely grease up the bunk boards with dishwasher soap when loading the boat from the water- you'll want to make sure nothing's binding.
posted by jenkinsEar at 2:33 PM on June 6, 2011

my 22' sailboat (a 1970 Magregor Venture, if you're curious) rides on 2"x6"x10" bunks and no rollers at all.
I hauled it 40 miles each way to the nearest lake a dozen times last year with no problems, and I'm betting it is significantly heavier than your 16" aluminum boat.
posted by namewithoutwords at 6:29 PM on June 6, 2011

Response by poster: Well, I'm going to give it a go without the keel rollers then.
posted by fimbulvetr at 5:38 AM on June 7, 2011

Response by poster: So, round trip with the trailer, 1100 km in total, no keel rollers and no problem. Guess they aren't needed after all . . . . now I just have to figure out which rivets are leaking . . . .
posted by fimbulvetr at 6:21 AM on June 13, 2011