trailer construction questions/suggestio

-- Last Updated: Jun-23-14 10:27 AM EST --

A friend has asked me to help think thru a retrofit of an existing tin boat trailer to a kayak trailer. Like most rowboat trailers it has a long tongue and low frame. Trailer is now just a steel frame with 4"x8" sheet of plywod mounted as a floor (width is 4'x8' plus the +/- 10' tongue). Capacity will be 3-4 boats.

We're considering removing the plywood floor but for two reasons:

1. it might protect boats from stones
2. it might make for a nice floor if sides were ever added

Is #1 really a concern? Anyone have a trailer where the boats ride low, say at axle height, and do they get dinged by stones?

Next question is frame material to hold the kayaks. I was thinking welded steel to keep it strong, buddy was thinking wood or PVC to keep it light...

Check out Oak Orchard Canoe in NY
Dear Slush paddler,

They sell premade kits to convert older boat trailers to canoe and kayak haulers. They may have something that will save you some time and farting around.


Tim Murphy AKA Goobs

I will do that, thanks for the tip. No sense reinventing the wheel!

I used threaded
galvanized pipe I had cut and threaded at my local home depot. The pipe and all the fittings cost about $75.00 The floor is 2 X 10’s covered with 3/8"plywood. The legs are screwed into a flange bolted though the floor and another flange under the floor so the rack won’t pull loose in the case of a panic stop. I added ratchet straps on the front and back and that took away any forward/backward sway. Here’s some pics

Good luck with what ever you decide


If you use PVC
I can tell you I have a pick up rack made out of 2" schedule 80 which has held up well but I would not go any smaller and I don’t know that I would trust it on a trailer.

If I was doing my trailer over, I saw someone build a 4 by 8 box 2 feet tall on a trailer then put a set of crossbars on it and used cartop kayak carriers. Very slick, gear went in the box.


Two sites for support

Keep the plywood but bore holes with a hole saw letting air thru and water out. Sand and Paint everything well.

If you lay down 2 transverse 1x4 across the ply at 2 places where the yaks will be supported maybe at the bulkheads then dry wall screw nail with a drill…no regular nails here…probably glue nails with yellow wood glue…screw on a 1x at the center vertical rack strut…at the bulkhead area: forming a 90 degree L structure.

Laying wood flat on ply is asking for rot so is best setting the wood into a thin sealer and inspecting. I’m writing the transverse for strengthening the ply floor.

Screw in 2 steel angle supports from transverse to butt mate. Angles are at Home Depot in fencing.

Set up 2 1x4" vertically of the 2 90 degree floor braces you screwed down.

Add a horizontal 1x4 wide so 2 hulls are carried: a tee.

Diagonal brace the vertical of the floor from center plywood.

Add a second vertical, transverse yak holder and floor brace.

Tie the two verticals together with a longitudinal brace…fore and aft… running over the yak holding 1x.

Throw a block into this joint so you can nail fore- aft to vertical.

Find a position for 4 angle braces, 2 each vertical, running from trailer sides to verticals.

Looks like a bare house roof frame. Requires clear wood free of large knots. Fir or western Hemlock #1.

Apply spar varnish.

Done. Room for 4.

The kayak foam blocks are highly recommended.

Foam supplies cushioning and wide support at low effort as the hull settles into the foam. Foam blocks have a strap tunnel down the insides for using a cam strap…parts from Seattle Fabrics…to cinch the hull to foam and then to whatever is handy for holding foam and kayak down together.

Angle irons will support a shelf for the foam on those T members. Then you need a brake board for holding foam on when braking hard.

Reads as complex, yes ? Well, the structure is a machine form so yes it’s a hassle errrr creative project.

Opinion here is the pipe stanchions will crack, lack support for the heavy pipe. ?

What you really need is a welder. Wood and cast iron passed from this scene well before WW2

If you search in Google Images for kayak trailer racks…there are ideas in there.

Our old Triton snowmobile trailer…
had a plywood floor with the kayaks riding not far above the wheels.

I don’t know if stones kicked the bottom much, but I can tell you that any time I drove over a wet dirt road there was always mud on the underside near the wheels. However, these wheels did not have fenders, and they rode directly under the plywood. Newer versions of this trailer went to the more typical plywood sitting BETWEEN (not over) the wheels, which have fenders.

My current trailer does not have a floor, but the kayaks also ride up higher.

Good luck, and post a pic here when it’s done,

You might be able to retrofit a canvas tarp if rock dings are going to be a problem.

Trailer build
I’ve done trailers with wood bunks, with threaded pipe, and seen PVC by someone else. Don’t do the wood, things loosen up over time. Mine was solid, had reinforced corners, treated lumber, painted well, Spax screws, etc. I overbuilt it and then some. Still had trouble with flex over time. Threaded pipe, even galvanized, will rust or eventually break at the point where it meets the flanges, even when painted. It’s the weakest part of the structure where the threads are cut.

I ended up going to a welder and had him make A shaped frames that bolt on to my old Dilly trailer. Stabilizers connect the front A to the back A and the whole thing can come off with four big bolts if necessary. Each A has two “arms” that come out at a slight upward angle. Chain links are welded under each arm to make strapping easier. I’ll post pics if you want to see it.

Anyway, go steel, keep it touched up, and it’ll last longer than all of us.

if I understand your description right
…then this is sort of the design I was thinking of. So the boats sit inside the angle created by the ‘A’ frame and the arms welded to the ‘A’ frame. One kayak on either side of the ‘A’ frame and perhaps a smaller one slid through the A framing. do I have that correct?

I know that only allows 3 boats but my main goal is to keep this compact and light and if possible, low. So this would work well.

Agree on the pipe

– Last Updated: Jun-24-14 11:14 AM EST –

I've been told I'm wrong about this several times here, but I've seen lots of pipe-built structures crack when subject to vibration, and it's always where the threads start, adjacent to where a pipe screws into a flange. It's a bad method to use on trailers.

A properly welded connection lacks the *abrupt* transition across the joint that you get with pipe, simply due to the filling provided by the weld, (and with pipe the situation is all the worse, having that built-in stress riser located there), and it's a cinch to broaden the area of contact and stress even more with gussets or other reinforcing.

right ! but if the mill is nearby at 15 cents BdF

FYI there are steel calculators online.

using roof framing as a guide…in Google Images…draw up a structure for angle/rectangular iron from a supplier. ask.

set the pieces on floor n drill holes…bolt together and go with that before taking the structure to a welder.

use black steel short bits from a supplier. drill a pilot hole 3/16th’s then a .25" hole for a grade 5 bolt.

Carr has bolts with unthreaded shafts for say 1/8th x 2" angle

rod/steel is available from McMaster Carr

thanx datakoll

– Last Updated: Jun-25-14 9:12 AM EST –

You just gave me an idea to streamline things a bit.

I take back all my negative comments!

Pics would be good.

I have a 5x8 ut trailer that has been kept for gathering wood behind the tractor that could be dual purposed with a rig like that. I have some 3 in channel and a welder but I need a plan.

Doing a A frame I could possibly use the front and rear stake pockets boring a 1/2 in hole through the pocket, A frame, and trailer frame and use a hitch pin with a hairpin to make it easy on easy off.

Tounge length is my only concern.

Utility trailer
I use my 8 X 5 utility trailer with 2 X 4 pockets on the perimeter of the frame where 2" X 4" uprights are mounted with crossbars at the deck level to set the insertion depth in the pockets and crossbars at a higher level for the boat bunks. There are also uprights which are attached to the crossbars that create slots for the kayaks to be carried on edge. The crossbars are heavily padded for a nice soft ride. The uprights are padded too, for protection of the boats.

There are four of these crossbar units from front to back of the trailer and each support crossbar is mounted to conform more, or less to the on edge contour of the kayaks, so the kayaks are equally supported at four locations along their length. The bunk units are retained in the pockets with bungee cords.

Normally I only carry one kayak in the center slot, but there is room for three. The longest boat must be carried in the center.

If the kayaks overhang the rear end of the trailer, I think it is important that the bunks are high enough that the kayaks will be about windshield height for following vehicles. And of course you will need to red flag at least the longest protruding boat.

i did that
My first kayak trailers were a speedboat trailer and a motorcycle trailer.

On Both I added a flatbed then removable saddles so I could have a flatbed for moving and a kayak trailer.

I have since bought a Malone Micro-Sport and added a plywood bed tyo hold gear.

bookshelf rack

interesting spinoff: 2 bookshelf 2x4 walls with custom pockets for your bats to slide into and thru.