Trailer Bunk Height Adjustment

H

hardee

New member
I have a Pacific Tandem bunk trailer, galvanized, for my 22 Cruiser. When backing down the launch ramp I often have to back to where the rear pickup tires are into the water, almost to the bottom edge of the wheels. Sometimes I still have to work to get the boat to slide off the bunks, which usually means drive forward again, then back and stop quick to get the boat to slide back on the bunks before it will float off or float to where I can pull it off by hand.

My assessment is that the boat needs more water to float off, so I either need to back farther into the water, have a longer trailer tongue or have the boat sitting lower on the trailer so it will float sooner.

I have thought about a tongue or hitch extension, a sliding tongue extension permanently on the trailer, or…..

My current thinking is this. (Since the boat is going to be off the trailer for about a week getting bottom paint.) I would have a good opportunity to do some trailer work. I am looking at changing the height of the bunks above the frame and axels lower the bunks about 2 inches. It appears to me that there is room for that without adversely affecting the ground clearances adversely. (The brackets are made by Pacific on an individual basis so they don’t have a set for a 22 foot C-Dory in stock on the shelf, and they run about $28 each, so it is not an inexpensive job, and then there would be new stainless hardware and maybe a new carpet layer as well.

I’m wondering if anyone has done anything like this before? If anyone can see any problems I am going to run into before a actually get there? Or, if there is a better way to address this issue, what is it?

The reasoning for doing this is that now I am getting “dragging lines” or “slide lines” on the bottom from where it is sliding on the bunks (the two long inside ones), and I don’t want to be wearing off the bottom paint as it is softer than the gel coat. It seems like this would be a good time, and I would rather have it better than good, not just make do….

Harvey
SleepyC:moon

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I have lowered my bunks as low as possible and still have the same issues on low inclined ramps. Especially on the start of a cruise and the boat is fully loaded. I am thinking of using teflon liners on top of the bunks to ease unloading. My trailer has tandem axles and 15'' tires which I like, but does give it extra clearance.

Jim.
 
Are you using the ramp at John Wayne? That is a fairly steep ramp, and I have never had a problem there...

But I have the same problem at places like Powell--where it is a shallow angle ramp.

I have only altered the bunk height with the boat on the trailer. To me that is the only way to do it properly? I did that on the current trailer. Used both a trolley automotive jack and a couple of barrel hydraulic jacks. Took the inner ones as low as possible. Then lowered the outer bunks to just let the boat rest on the inner bunks. Brought the ends of the bunks to fit the boat hull. That way you get the best fit.

Most of the 22's fit OK between the wheel fenders--not so on the 25's--they can be quite close. But it depends of the width of the axle.
 
I looked around for clearance/fit issues. The current “bunk risers” are 6.5” up from the trailer cross members. The risers are not adjustable, and they are all the same length, but Pacific says they are custom built to fit particular specific positions so they would come marked for their correct positions.

Measuring all the way around looks like I should be able to go with 2 – 2.5 inch shorter risers for replacement. The Side guards, (Side guide bunks) will fit right up to the bottom of the top lap-strake step if I go down 2 inches. I can move the side bunks down to fit if I need to.

I do sometimes launch at John Wayne, but last year I did more from Port Townsend Boat Haven than from Sequim. Both ramps are fairly steep, but I often wind up dragging the last 3-5 feet up on the trailer even on those ramps. It always works better if the boat is stern heavy, so I usually load everything that I need to take off the boat back in the cockpit before I go for the trailer.

Jim, Yes I have thought of the “Teflon” bunk pads, but still have concerns about the effect on the bottom paint, when I have to slide on them. BTW, I saw your boat at Alert Bay last summer, but missed seeing you there. You and another C-Dory came in about the same time. I got to visit with them but missed you.

Bob, I probably wouldn’t do the adjustment with the boat on the trailer, but I will have factory EOM parts, just shorter. I could put the forward and aft brackets on, set the boat on the trailer and then jack the middles up to tight against the hull for fitting, maybe. I have to jack and block the trailer up about 8 inches to be able to get under it at all, so it will be easier to do it with the boat off the trailer. If the brackets don’t look like good matches, that could make a difference.

Harvey
SleepyC:moon

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Interesting you don't have adjustable bunks. Many trailers do--So what you need are the galvanized "risers" between the cross members and the bunk bracket--which are XX" shorter.

It sounds like a couple of inches should help--but agree, since you cannot lower them, that it is better to replace when the boat is off the trailer.
 
I decided to put Teflon bunks on last summer. I removed the bunks to install, and I'm glad that I did. The first thing that I noticed was that several of the galvanized lag screws that hold the bunk to the risers had failed. The wood had rotted right around the screw. Second, the risers have an attachment plate at the top that swivels. Mine were distorted from the weight.

So I got new wood bunks and two sets of new risers. I now have them both front and rear of the cross members. Twice the support. I also put them on the lowest possible position. That was spooky because my calculation was that I would have 1/2 inch of clearance between the boat bottom and the frame. My calc was right, and having just that amount of clearance hasn't been an issue. I would have to mangle my doubled-up risers to create a clearance issue.

Two inches lower and plastic bunks made a surprising difference. Wish I'd had this setup at Moutcha Bay last year. I had to back in to the point where my exhaust burbled. Not good.

Mark
 
Mark,

I know what you mean about the bolts in the wood. I rebuilt my single axle Pacific trailer before I sold it. New bunks, new hardware, new SS bolts, nuts and washers.

To negate the problem of the bolts or nuts turning in the wood, I cut the heads off some extra long bolts, bent them into a 90 "L" shape and routed out a slot in the top of the bunk, next to the hole. That let the bolt sink well below the surface. I then buried the "L" portion of the bolt into that slot and filled it with 5200, before I covered with new carpet.

I'm considering doing the same on this job, depending on how the bunk boards look when I get the boat off them.

Harvey
SleepyC :moon

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One problem I have seen with the lag screws (and sometimes bolts) is that the galvanized metal re-acts with the chemicals used in the treatment of the wood for bunks. This used to be copper sulfate and other copper containing compounds which would react with the galvanizing. In our highly treated pilings, and lift bunks, we use all Stainless steel fittings against the wood--or a barrier of an inert gasket material.

I replaced the galvanized lab screws in my bunks with Stainless, and it seemed to have stopped the deterioration about the fastener.

Aluminum is also attacked, and isolation with similar material will prevent its deterioration.
 
I believe the bolts, nuts etc on my first trailer were all galvanized. I believe that Pacific is now using all stainless, from what I way on their site, but I have not confirmed that with them.

The bunk boards were treated Douglas Fir.

Harvey
SleepyC :moon

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Harvey,

How are bunk risers bolted to the cross members ? Are they not u-bolted ? And are the bunk risers fastened to the side of the cross members?
The risers on my Load Rite come in various lengths, and are slotted for adjustment.
alan
 
I decided to put Teflon bunks on last summer. I removed the bunks to install, and I'm glad that I did. The first thing that I noticed was that several of the galvanized lag screws that hold the bunk to the risers had failed. The wood had rotted right around the screw. Second, the risers have an attachment plate at the top that swivels. Mine were distorted from the weight.

So I got new wood bunks and two sets of new risers. I now have them both front and rear of the cross members. Twice the support (and they look sturdier than the originals). I also put them on the lowest possible position. That was spooky because my calculation was that I would have 1/2 inch of clearance between the boat bottom and the frame. My calc was right, and having just that amount of clearance hasn't been an issue. I would have to mangle my doubled-up risers to create a clearance issue.

Two inches lower and plastic bunks made a surprising difference. Wish I'd had this setup at Moutcha Bay last year. I had to back in to the point where my exhaust burbled. Not good.

Mark
 
Harvey,

Another approach worthy of thought is move your boat further back on the trailer.
Looking at your trailer it appears you can move your axle back maybe as much as a foot or more, than position the boat further back.
You could possibly move your boat back as much as a couple of feet while maintaining proper Tongue weight. Than move the winch pedestal (or whatever it's called) back.
If you're not comfortable adjusting the trailer setup by all means take it to someone who can.
Sooner or later rust is going eat your truck alive.
 
Moving the boat back one can loose the support of the transom by the bunks. That may have adverse affects on the hull. (Unless some how you extend the bunks--and have support under them. Can do the same thing with a tongue extension, pole extension, or a longer tongue--also probably cheaper...(the latter), but all of these do affect trailer towing balance..
 
thataway":2ohqlsgg said:
Moving the boat back one can loose the support of the transom by the bunks.
Click to expand...
Yes this is true, the bunks than need to be moved back also.
My current King trailer allowed for all these adjustments.
Not every trailer has this flexibility, but if however Harvey's trailer does he should certainly consider the possibility his boat was setup too far forward.
The setup on my 25 by the dealer in Washington was horrible, fought it all the way back to Anchorage because they didn't take the time to do it right.
Just saying, it warrants a look.
 
I can see where some of the 4 x or 6 x upright bunks which are conformed for the deep V boats could be moved back and still give good support.

But most of our boats are on bunks which have 2 x 4 or 2 x 6 bunks, with the 2" dimension up and down--and these can sag without support from the trailer frame.

How far back does one need that difference, and keep truck wheels out of the water? At powell, I end up with truck exhaust in the water or at the surface. I was able to drop it down slightly--but not able to go to Powell any more, so don't know if that would have helped to keep exhaust out of water...
 
Currently my boat sits with the transom directly over the aft end of the bunks, (all 4), and just at the end. Seems like a lot of gymnastics to go through to move axles, bunks, and winch post to get 6" to a foot farther back into the water. Wouldn't lowering the bunks accomplish the same result, maybe easier?

Harvey
SleepyC :moon

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My trailer has 2 x 6 bunks, lying flat on their sides. The center two are the long ones, 12-14 feet (IIRC) and the outer bunks are 4-6 feet long with the outer boarder just inside of the chines by an inch or so. With the Load guide bunks giving some slack, the boat can move about an inch either way from center when loading. (Of course, once loaded and tied, it doesn’t move at all.)

The bunk risers (Pacific calls them “bent top risers” as opposed to their “adjustable risers” – which have an angled bracket that is drilled, and bolts to the vertical piece), are 6 inches tall from the trailer cross member. The riser has a “saddle” that sits down onto the cross member and then is bolted below to pinch the cross member and maintain position.

If I order new bent top risers that are 2 inches shorter (4”), should I have any concern that the geometry of the bunks after lowering them that 2” would be any different than they are now at the 6” level? I would be putting them on in exactly the same positions as the current risers.

One concern I have is that getting the old bolts out will require digging into the bunk from the top because it is a lag bolt that is sunken into the wood on purpose by the factory to keep it from spinning when they tighten up the nut onto the riser. Those nuts are pretty rusty and don’t come off easily. I know that from my experience with replacing bunks on a previous Pacific trailer. I really don’t want to replace bunks at this point but could if I have too.

Any thoughts are appreciated. Thanks you.

Harvey
SleepyC:moon

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Harvey,
I went thru your photo albums, and enlarged the photo in your Avitar. I don't see any major problems. You may have to move the winch post and the bow roller slightly--so look at what that is gong to do. Also any chance that the bow would be more likely to contact the trailer frame as loading? It looks as if you have a padding over the forward trailer cross member.

The side bunks may be closer--so you may have to move them out a little.

If you have to remove the lag screw (lag boltI), you can move the entire bunk forward or aft a few inches, giving you a "fresh hole" for the lag screws. You may want to fill the old hole with epoxy, to prevent rot.
 
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Thanks Bob, Much appreciated.

Good idea on moving the bunks, probably aft a couple of inches. That might help some in the quest for deeper water :D

It is sounding more like it should work. Need to be able to do this while the boat is at the yard for bottom paint. No project ever lives by itself. :oops: :roll:

Harvey
SleepyC :moon

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