Trailer Bunk Adjustments

[c-level]

I've searched the forum and although many of you folks have rollers, I'm looking at getting a used trailer for a 14' rib that has two bunks. One of the threads I read said you should position the carpeted bunks so they are at the edges of the RIB, just before where the inflated tubes meet it. I thought this was interesting as most fiberglass boat trailers usually have the bunks about half way from the keel to the outside of the boat.

Is that how most of you rig your bunks when you don't have a rollers? Is there a certain height I should have the bunks or do I just try to do it high enough that the bottom of the rib doesn't hit the trailer fender?

[seasdes]

After years of playing with boats I have learnt that mos of the boat's weight needs to be supported by the keel rollers. The bunks and side rollers are there to hold the boat level while trailering.

Therefore, firstly set up the keel rollers o they are all supporting the boat's keel. Then adjust the bunks or side rollers so that there is a 1" gap (maybe more) when the boat is on the trailer. This then allows the boat to be unloaded and loaded with the minimum of effort.

[beamishken]

I wouldn't have them at the tube flanges, the usual thing is to get the bunks under or near the chines as the internal stringers are often glassed into the stringers,you therefore have max support

all the us trailers ive had have had no keel rollers fitted & totally rely on the bunks

if it has keel rollers I would have the bunks up tight to the hull rather than down as suggested above as the boat will rock about when towing

[jyasaki]

For me, placement is more of a convenience, as the aluminum hull is strong enough to handle bunk placement just about anywhere.

For a glass RIB, I suspect it's likely the same for the most part, as long as you have adequate support (meaning long enough bunks.) I like having mine just inside the chines, as it gives a bit of self-centering (unless you're way off when loading), and makes it easy to tell at a glance that the boat is centered. In towards the keel will allow for a bit of play side-to-side; you don't want a couple of inches offset causing a bunk to ride on a tube (because you likely will recover in rougher than ideal conditions someday, and have to trailer with a less-than-perfect loading.)

Height will be determined by clearance over the fenders (this is one aspect where RIB's are at a disadvantage over hard boats - they're broader at a lower point, so must ride over the fenders where hard boats can nestle between.) I'd advise against having the boat sit nose down on the trailer, as it won't drain (and rain may pool causing an overload of the trailer.)

Make sure that you have adequate transom support (bunks should extend beyond by a few inches - more of that misloading fudge factor; also makes for a handy step should you need to grab something in the boat), and I find some sort of stop at the bow that also indicated bow height handy as well (say a V-block over the bow eye or something like that.)

Luck;

jky

[c-level]

Many many thanks for all the helpful suggestions. I came across a aluminum Triton pwc trailer, it is in excellent condition and the previous owner says he used to haul a 14' Rib on it. When I looked at the picture of the trailer it seems like the bunks are low, way to low to hold a 14' Rib on it.

I was thinking I could buy new bunk brackets for it, although the Triton trailers are supposed to be fully adjustable (I cannot see how the adjustments could possibly allow for the bunks to be raised above the wheel wells in the stock configuration). I was reading up and it is not recommended to use other metals with aluminum trailers as it causes severe galvanic corrosion. Even if I get aluminum brackets I would still have to use stainless hardware, wouldn't that also cause a problem? Is there another way I could raise the bunks above the wheel well?

[jyasaki]

I doubt you'd have much corrosion problem on a trailer. Dissimilar metal is more of an issue on stuff that lives in and under saltwater.

Longer brackets are the ticket; you may have to change the design of whatever is on there now, though.

My trailer has risers that are a square U shape with a slot lengthwise down the middle, maybe 12, 15" long. A U bolt goes around the trailer crossmember, and a plate on the other side facilitates bolting it on. The slot allows for adjustment. All hot dip galvanized. A single bolt hole at the top allows for the tilt of the bunks to be adjusted.

On the bunks, a fairly long support bracket bolts to the wood (extends about a foot to either side of the riser attachment), and the connection to the riser is at the center (I need to have some new ones of these installed, as these are rusting out at this point.) In addition, to get a bit more height, I bolted in an additional piece of 2x8 between the bunk and the brackets.

Here are the risers I have (or similar, anyway):
12" Swivel Top Bunk Bracket Complete 1/2" - Champion Trailers

I haven't been able to find the support pieces online, may have to get them made up by a metalworking friend.

jky