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Lets Talk Trailer Bunk Placement...

brianZ71

Member
I've done quite a bit of searching and have found many different opinions on trailer bunk placement. What is the consensus nowadays? The three most popular ideas i'm seeing:

1.) Traditional boat style bunks running front to back, placed out under the chines. boat sits on the wide side of a 2x4



2.) Trailex style bunks that go sideways under each side of the boat



3.) Cut a couple of 2x10's to match the curve of the bottom of the boat




I'm leaning towards #1. Opinions? Experiences?
 

danpal

Active Member
I like a variation on option #1 which takes a little more work but I think it provides better support. It's a contoured bunk design that I found on the Sunfish Sailor Yahoo site. John Howard provides a whole photo essay on how to build it under "Skylarkmk1s Trailer" in the photos section. I've used it for 2 years and really like it.


 

tag

my2fish
nice timing! I currently have my trailer set up like picture #1 - the bunks were originally set up to close to the center of the boat, but I moved them further out closer to the edges.

but, I was thinking about switching over to a system more like picture #3 - but instead of just using a 2x10, I'll attach a 1x4 or 2x4 on top of the scribed 2x10, to give a wider bunk surface that still follows the profile of the boat.

part of my reason for the switch is to make the perpendicular 2x10 boards extend out so that I can add a vertical post up and the option to put a 2nd set of bunks on for carrying 2 Sunfish at a time.

any thoughts on padding under the bunk carpet? I thought I've seen people use thin foam for extra cushioning.

cheers,
tag
 

Geophizz

Member
I used John Howard's design, and it looks very similar to Danpal's design above. I've read that you should always support the Sunfish at its chines, as that is structurally the strongest location. There is very little internal structure or support inside a Sunfish, almost none actually, so any bump the trailer hits will translate into flexing of the bottom of the hull. Those flexing effects can cause the foam blocks to come loose, and eventually can cause structural weakness in the hull that manifests itself as the "oil can" sound that older hulls can make when riding over waves. If you're mainly a cruising sailor, it won't affect you, but it's the death knell of a racing boat.

Since I've built my bunks I've seen a lot of trailers from higher level Sunfish racers, and they almost to a person carry theirs upside down, but that really hampers your ability to sail solo.
 

brianZ71

Member
Yeah I hauled mine upside down in the back of my truck last season. It was tough as I mostly sail solo, but I made due. I definitely want to go right side up now that I have a trailer. I'm liking John howards design. That may be a winner.
 

L&VW

Well-Known Member
Yeah I hauled mine upside down in the back of my truck last season. It was tough as I mostly sail solo, but I made due. I definitely want to go right side up now that I have a trailer. I'm liking John howards design. That may be a winner.
I agree with your selection, but I "car-top" my Sunfish, so I can only reply in theory. ;)

Having acquired a Sunfish with loosened internal blocks, I'd wish for a trailer that supported the Sunfish as though it were on water. (Or as though I were to trailer :oops: an egg). Working backwards from The Ideal Support, I'd want a hammock, bunk-bed mattress, or a net of nylon strapping; admittedly, none of those are practical, but most trailers are over-built for ~140 pounds, and regardless of what you load on your trailer, every pothole and speedbump will hammer the loadtwice. :eek:

If one is going to use wood, I'd go for John Howard's design, but with 1x's all around, or pressure-treated 5/4s. "Yes" to cushioning—but strap the Sunfish down tightly, so that the cushioning is fully compressed.

JMHO—just based on my "loosey-goosey-egg" theory. :) FWIW...:rolleyes:
 

brianZ71

Member
I agree with your selection, but I "car-top" my Sunfish, so I can only reply in theory. ;)

Having acquired a Sunfish with loosened internal blocks, I'd wish for a trailer that supported the Sunfish as though it were on water. (Or as though I were to trailer :oops: an egg). Working backwards from The Ideal Support, I'd want a hammock, bunk-bed mattress, or a net of nylon strapping; admittedly, none of those are practical, but most trailers are over-built for ~140 pounds, and regardless of what you load on your trailer, every pothole and speedbump will hammer the loadtwice. :eek:

If one is going to use wood, I'd go for John Howard's design, but with 1x's all around, or pressure-treated 5/4s. "Yes" to cushioning—but strap the Sunfish down tightly, so that the cushioning is fully compressed.

JMHO—just based on my "loosey-goosey-egg" theory. :) FWIW...:rolleyes:
Yeah, and I'm using an 18' boat trailer for this. It was sprung way heavy, but i took apart the leaf packs and am just using the main leaf. The trailer itself is pretty heavy, so it's pretty soft now. I may even go so far as to weld on some small boxes with scrap steel and add a couple bags of sand or something. I've got an ad on craigslist looking to trade this for a jetski trailer or the like, but this will work for now.

edit: the trailer is 18' overall. Not made for an 18' boat.

My plan is to pad the bunks and strap it down tightly so that it bounces with the trailer. I've tossed around the idea of putting the bunks on some sort of springs, like the cab on a big rig, but I think that would unnecessarily complicate things.
 
a couple years back i made my trailer into a double decker for sunfish #2. in doing so i cut a 2x into four 2' carpeted pieces and split them over four brackets. each bunk pivots around a single bolt and nylon nut which allows it to conform to the hull of the fish...would work with a single trailer too.
 

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RomanSailer

Member
I spent a bunch of time trying to pattern and cut bunks, crossways and lengthways for my sunfish, and decided there has got to be simpler way. Knowing that the chines are at the strongest point, I decided to concentrate there. What I ended up with is two 2X4 that run across the trailer. On the end of each I attached an upside down U-shaped saddle of 2X4 pieces, spaced to be right under the chine. By doing one at a time, I could get optimal contact and angle, using a through bolt and woodscrew to lock in place. Padded each one and viola. And for longer term storage I just turn the boat over on the same blocks and pads. I can also just pull off the thwart-wise 2X4s and use the trailer for other things (the Old Town or the Laser or a pile of 2xX lumber)
 

tag

my2fish
I spent a bunch of time trying to pattern and cut bunks, crossways and lengthways for my sunfish, and decided there has got to be simpler way. Knowing that the chines are at the strongest point, I decided to concentrate there. What I ended up with is two 2X4 that run across the trailer. On the end of each I attached an upside down U-shaped saddle of 2X4 pieces, spaced to be right under the chine. By doing one at a time, I could get optimal contact and angle, using a through bolt and woodscrew to lock in place. Padded each one and viola. And for longer term storage I just turn the boat over on the same blocks and pads. I can also just pull off the thwart-wise 2X4s and use the trailer for other things (the Old Town or the Laser or a pile of 2xX lumber)
can you post some pictures?
 

RomanSailer

Member
It took awhile to get computer time (teenagers!) but these are the saddles I use on crosswise 2X4 . you can see the thru bolt, which I placed above center to give more support and less chance to split. Once I got the tilt right, I put in a screw to lock it in place. And I had to notch the middle of the crosspiece to accommodate the center keel and keep center of gravity low. In the photo, the boat is upside down for the winter, with heavy plastic cover sheet, but when right side up, it sets right at the chine.
IMG_2127.jpgIMG_2126.jpg
 

L&VW

Well-Known Member
"I've tossed around the idea of putting the bunks on some sort of springs, like the cab on a big rig, but I think that would unnecessarily complicate things."
• There are some spring-loaded steel shock-absorbing "isolators" that are discarded after shipping "ride-sensitive" equipment. They are about 2" tall, with a 3" base, and attach using four screws, with a single threaded hole at the top. I have a few, but you'd need a couple-dozen to isolate one 130-pound Sunfish.

• Some axles on cars have a diagonally-placed shock absorber. I cartop my Sunfish, but I'd try mounting an automobile shock absorber diagonally on any trailer "over-sprung" for the 130-pound Sunfish.
 

Zrtsixx

Member
I also liked the John Howard set up. I placed the bunks over as far as could on the trailer and used a treated 2"x6"x8'. I used the compass method to trace the cuts on the bunks. In retrospect, I would have used 2"x8" though. I did not cut the bunks at an angle, but I figured out an alternative. The clearance between the hull and the supports under the trailer was about an inch. It seemed a little too tight for me. So I cut some other pieces to lift up the bunks. When I screwed them into the bottom of the bunks, I noticed that the outer frame of the trailer was a little higher than cross rails. By placing the cut wood on the outer rail, it caused the bunk to lean in to the center of the trailer a little ways. Plus, the bunk is resting on the extra piece of wood between the forward cross rail and the out side rail towards the front of the trailer. It is far from perfect, but I think it will do!Trailer lift 2.jpg View attachment 8084
 

Zrtsixx

Member
I also liked the John Howard set up. I placed the bunks over as far as could on the trailer and used a treated 2"x6"x8'. I used the compass method to trace the cuts on the bunks. In retrospect, I would have used 2"x8" though. I did not cut the bunks at an angle, but I figured out an alternative. The clearance between the hull and the supports under the trailer was about an inch. It seemed a little too tight for me. So I cut some other pieces to lift up the bunks. When I screwed them into the bottom of the bunks, I noticed that the outer frame of the trailer was a little higher than cross rails. By placing the cut wood on the outer rail, it caused the bunk to lean in to the center of the trailer a little ways. Plus, the bunk is resting on the extra piece of wood between the forward cross rail and the out side rail towards the front of the trailer. It is far from perfect, but I think it will do!View attachment 8086 View attachment 8084
Trailer lift 1.jpg
 

bill_k

New Member
As far as padding for the bunks, I found some above ground pool padding that goes under the pool liner. It is very condensed and holds its shape very well. I've had it on my bunks for 3 years and it still looks great. I used large washers with the screws to hold it to the wooden bunks and then wrapped the outdoor carpeting around the bunks.
 

vela

New Member
It took awhile to get computer time (teenagers!) but these are the saddles I use on crosswise 2X4 . you can see the thru bolt, which I placed above center to give more support and less chance to split. Once I got the tilt right, I put in a screw to lock it in place. And I had to notch the middle of the crosspiece to accommodate the center keel and keep center of gravity low. In the photo, the boat is upside down for the winter, with heavy plastic cover sheet, but when right side up, it sets right at the chine.
View attachment 8082View attachment 8083
Did you finish these with anything?
I have a support made out of 2x4's and am wondering if boiled linseed oil might be a good idea.
 

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RomanSailer

Member
I did not use any finish. I would use whatever is at hand. Poly if thined well is a good choice. tung oil. linseed. sikens, if its laying around. My experience is that if you treat the wood, the treatment will last about two years, so you have to re-apply, and the project will last about 10. If you do nothing, it will last about eight years. By which time I want to do something else anyway.
 

Repete

Sunfish1909
I used John Howard's design, and it looks very similar to Danpal's design above. I've read that you should always support the Sunfish at its chines, as that is structurally the strongest location. There is very little internal structure or support inside a Sunfish, almost none actually, so any bump the trailer hits will translate into flexing of the bottom of the hull. Those flexing effects can cause the foam blocks to come loose, and eventually can cause structural weakness in the hull that manifests itself as the "oil can" sound that older hulls can make when riding over waves. If you're mainly a cruising sailor, it won't affect you, but it's the death knell of a racing boat.

Since I've built my bunks I've seen a lot of trailers from higher level Sunfish racers, and they almost to a person carry theirs upside down, but that really hampers your ability to sail solo.

I run with John Howards design as well. A key to his design is that is also incorporates the use of keel rollers as the actual load points. The tailor fit bunks help with on and off of a nicely waxed boat. These bunks should be equal if not just a hair less in height to allow the keel rollers to engage the load. Yes, bearing on outer bunks only will flex the foam blocks free over time. My '79 boat already has some "oil drum" , but it was a pre existing condition. Guess what my next project is ;) .
 

Charlie Braun

New Member
I like a variation on option #1 which takes a little more work but I think it provides better support. It's a contoured bunk design that I found on the Sunfish Sailor Yahoo site. John Howard provides a whole photo essay on how to build it under "Skylarkmk1s Trailer" in the photos section. I've used it for 2 years and really like it.
I can't find the photo essay - I think maybe it's disappeared? Anyone have any ideas where I can find some info on how to build the bunks below? They look like they're worth the effort. I have to get a hull crack repaired after my latest 4 hour trailer with standard 2x4 bunks that were in the middle of the hull.
Thanks,
Charlie

 
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Wavedancer

Upside down?
Staff member
I can't find the photo essay - I think maybe it's disappeared? Anyone have any ideas where I can find some info on how to build the bunks below? They look like they're worth the effort. I have to get a hull crack repaired after my latest 4 hour trailer with standard 2x4 bunks that were in the middle of the hull.
Thanks,
Charlie
Apparently, there are problems with the yahoo site, as of today. Perhaps if you check back in a while, you might be able to access the photo essay once again.
 

Geophizz

Member
The bunks have to be under the chines as much as possible, because there's virtually no structural support at the flat sections of the hull. I would stay away from any type of bunk that goes across the boat, as I've seen boats nearly cracked in half like so many eggs from bouncing on crosswise supports.

The only drawback that I've found to John Howard's design is that it can be difficult to get the boat off a dolly onto the trailer by yourself. You have to lift the boat over the highest spot of the bunk at the rear. It is awkward and sometimes the boat slips and falls onto the edge of the bunk. I think that shortening the bunks in the rear by about a foot would solve the problem.
 
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oldpaint

Active Member
Interesting point. When I retrieve my sf I plan on reconfiguring it to the John Howard design but I think it might be improved by ending the fixed bunks on a crosspiece of appropriate height at the rear of the trailer's fenders. I'd then use regular bunk supports which allow pivoting up and down at the rear. The bunk on them would be a continuation of the curves of the fixed portion but would allow for easier loading and unloading. It would be easy to build: just do the full length bunks then cut across them at the break point and have them rest on the same crosspiece that the forward section ends on. The crosspiece might have to be notched for the bailer.
 

danpal

Active Member
I've found that this isn't really much of an issue. The bunk carpeting makes it really easy to slide the sunfish along the length of the bunk. The dolly I use is homemade and pivots so the bow rests between the bunks and I can slide the sunfish onto the trailer. The dolly I made is very similar to Jim Manta's dolly except I added an additional crossbeam above the axle. I also upgraded the wheels to Harbor Freight 13" wheels since the plastic wheels tended to wobble.

upload_2013-9-16_16-56-54.png
 

oldpaint

Active Member
I did build a removable trailer bunk system based on the John Howard design. (When I'm not hauling the sunfish I take the cradle off the trailer and use it with a plywood box as a utility trailer.) It has 1x8 pressure treated carpeted boards sitting on treated 2x8's. The cross bracing is treated 2x4's. I've been playing with webbing crossing from the top of the port bunk to the starboard side bunk to support the keel, but its not shown in these pictures. Also the bolts holding the cradle to the trailer aren't tightened, since I wasn't traveling anywhere, just taking a few pictures.
cradle stored on garage wall.jpg Sunfish on cradle.jpg Bunk normal position.jpg Ready for Launching.jpg
 

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tag

my2fish
I did build a removable trailer bunk system based on the John Howard design. (When I'm not hauling the sunfish I take the cradle off the trailer and use it with a plywood box as a utility trailer.) It has 1x8 pressure treated carpeted boards sitting on treated 2x8's. The cross bracing is treated 2x4's. I've been playing with webbing crossing from the top of the port bunk to the starboard side bunk to support the keel, but its not shown in these pictures. Also the bolts holding the cradle to the trailer aren't tightened, since I wasn't traveling anywhere, just taking a few pictures.
Very nice work, oldpaint!
 

Geophizz

Member
Nice work Oldpaint! How did you get the back of the bunks to flex? I wanted to do that on mine, but could never figure out how to make it work right.
 

danpal

Active Member
Yeah, and I'd also like to see how you incorporated the plywood box for the utility trailer (something I've been thinking about for a while).
 

oldpaint

Active Member
Very nice work, oldpaint!
Thanks Tag
Nice work Oldpaint! How did you get the back of the bunks to flex? I wanted to do that on mine, but could never figure out how to make it work right.
Geophizz, The mounts for the bunks came with the trailer (from 1993 or so) and are pivoted, if thats what you mean. The same bunk mounts are used in the utility box pics below. To get the curve correct, I built the cradle in one piece, a lot of trial and error work, When I was happy with it, but before carpeting, I took off the top 1x8 (lag bolts hold it on) sawed that and then sawed the curved 2x8. All of it was done by eye, hmm that looks pretty good ,rather than following a plan.
Yeah, and I'd also like to see how you incorporated the plywood box for the utility trailer (something I've been thinking about for a while).
Danpal, here are some pics:
port side overall utility box.jpg
bunks utility box.jpg
tailgate open.jpg
Just a box with a tailgate. The picture above shows the 2x4 cross bracing for the top. The bracing sits in a joist hanger made for removable railings. the 2x4 also has right angles mounted at the top extending out 1/2 inch to catch the side of the trailer and hold it in. Both straps go over the two 2x4s and its very rigid. There is a 2x4 in the middle of the bottom to serve as a keel for the roller near the bow of the box. (that roller is so low the sunfish doesn't touch it) I also carved a piece of 2x4 on the front to serve as a prow to catch the bow roller bumper thing by the winch. I have to move the winch location back when I use the box because its only 9 ft long, not 13'9''.
The hinged end is a great idea, as well as the cleats!
Thanks Kent appreciate that. The cleats aren't my idea, Geophizz came up with that.
 
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oldpaint

Active Member
I forgot to mention that I had to slot one of each pair of screw holes on the end of the trailer that the bunk mount u bolts go through so the mount is plumb. This is visible in the utility box bunk mount pic above. For the Sunfish I use the outermost pair of holes.
 

L&VW

Well-Known Member
"...A key to his design is that is also incorporates the use of keel rollers as the actual load points. These bunks should be equal if not just a hair less in height to allow the keel rollers to engage the load..."
Just a mention that rollers elsewhere than the keel will put a serious bend in the hull. I do have to change my ramp design next spring! :confused:P7290019-004.JPG
 

signal charlie

Well-Known Member
Staff member
Just a mention that rollers elsewhere than the keel will put a serious bend in the hull. I do have to change my ramp design next spring! :confused:View attachment 12969
I'd avoid any load on keel rollers other than loading and unloading. If the boat is strapped down and the load concentrated on the roller, the fiberglass will crush and get soft....and the boat will take on water...and you'll wonder "where did that water come from..."
Ask me how I know and OBTW don't forget to inspect the keel when you buy a Craigslist boat... :)
Kent
 
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