Kayak trailer modification to add storage box

Hello everyone,

I need a little advice on how to secure a storage box like Yakimas’ rocketbox pro 11 on a Triton WV-1500 trailer.
I had tried contacting the place of purchase about setting this up, but they have currently gone silent on this and I have not been able to call them through the work hours.

He did say that they mount some bars down near the frame for the box to clamp on to.

I am totally clueless as to how to and what to use. Any assistance will be greatly appreciated.
Thank you.

I’m no expert. It looks like the rocket box attaches to roof rails on top of a car normally. You will need 2 bars on the trailer to simulate roof rails. I would try and keep one of them across the Y in the frame and one across the tongue. Looks like there are some holes in the tongue already.

If they don’t make adapter bars you will have to rig something yourself from pieces of box tubing or something.

I think if you lay the box on the trailer where you want it you will get an idea of what you need to add.

There are two uprights that support the front kayak support bar. Are those uprights spaced widely enough for the storage box to fit in between? If not, that will restrict where you can mount the storage box.

Otherwise, as bud16415 said, you can mount cross bars to the trailer and mount the box to those. To keep it simple, you could buy some Thule square bars for the cross bars and perhaps attach them to the trailer using U-bolts.

Also, if you plan to carry much weight in the storage box you don’t want it too far forward. It would increase the tongue weight too much. Better would be under the kayaks, centered a foot or so forward of the axle.

Do you have any additional pics of the trailer?
Do you want to have access to the box while the kayaks are on the trailer?
What size Rocket Box are you looking at.

It appears that trailer has a ‘V’ section for a jet ski hull. My initial thought is that you could have a shop install 1" tubing across the lower part of that area so the Rocket Box would fit under your boats. That would keep your COG low and should be an easy mod if you have the space. Most boxes fit many different bar types, so there’s no real need to buy specific bars. A welding shop would probably do it all for the cost of a set of new bars. Depends on your space, though.

Access to the box would be preferred. I was looking at the 11.

Mine is similar to jaytee’s trailer, though mine is larger and has upper bars for additional boats. I’ve been very pleased with the functionality. I considered using a Rocket Box style but found the lid mechanism/design took up too much real estate when open.

How would you assure that sea water would drain from the diamond plate box in the picture and not let road water in? I’m thinking about a 72 inch narrow box like that. Im thinking about adding some tilt to the box when the trailer is level and putting a valve in.

Can you share the mounting details? Was it just bracket bolts or did you put some kind of urethane pad in between the box and trailer to keep the galvanization from scraping off?

The box is aluminum so wear is not an issue and I’ve never had any water in it but adding a drain if it was an issue would be easy

You can also cover the bottom of the box with something like this, so the water would settle on the bottom without touching your gear: https://www.amazon.com/Herco-Purpose-Neoprene-Rubber-Waffle/dp/B01M0AG1LX

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I guess the fact that the box is aluminum is ok. I think I would want to add some vent ports though.

Drain tube hanging down

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Salt water will corrode and eventually pit aluminum, even creating holes in it if it’s thin enough. So if you do stash gear with salt water in an aluminum box, be sure to wash it out with fresh water when you get home. One option would be to spray the inside with rubber type coating (like bed liner spray or the ubiquitous FlexSeal).


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Who makes that box?

That’s a pickup truck box turned sideways.

My old truck box. It gets in the way of the bottom boat. I have carried short 8 to 10ft boats on top of the box during shuttles.

It has drain holes in the bottom with no water problems. The dust is quite dry.

O I thought it was a wide shallow box.

You may be able to use something like this, though storage would be a bit limited:


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Get a plastic tool box no rust.