Setting up Trailer for MilPro Mark V

AlpinetoOcean · 20 November 2024, 02:15

Hi RIBNet Community,
I'm a new owner of an older (1993) Zodiac MrkV HD. It came on an U-built trailer that has seen better days. Renewing the old trailer doesn't look practical. For one thing it is painted steel which I assume was chosen for its original life in freshwater. Here on the Pacific coast it has rusted heavily. So I found a used galvanized trailer that looks to have potential as a replacement.

Knowing that there was no way I would be driving the old trailer on the road, I had the Zodiac lifted onto the new trailer as a first step. It is a tight fit. The transom was ~8 inches aft of the end of the bunks so I added a longer length of 2x6 on top of the bunks to support it. You can see the end of the new wood in the photo below.

Once the Zodiac was on the new trailer the other issue that became apparent was that the main tubes are resting on the wheel fenders. Not too heavily, I'd say by about 1.5" or so.

So my plan is to set up a new pair of bunks and take the trailer to the boat ramp and get it off the trailer, park the boat in the marina and run the trailer home to fit the new bunks on the trailer and then retrieve the boat.

I have all the parts: 12" bunk brackets, U-bolts, new bunk carpet, stainless staples etc... I'm not sure if the 12" brackets will lift the tubes high enough off the fenders so I'm toying with the idea of laying down 2 layers of 10 ft lengths of 2x6 to get an additional 1.5" height. I know that's unusual but I also imagine this will give the bunks enough heft to better support the transom and the overall weight is no where near the 2200lb capacity of the trailer.

My specific questions concern the placement of the bunks. Currently I have the bunks about 48" from outside edge to outside edge. That puts them just inside the speed tubes. (I cut the fore end of the temporary bunks at an angle to accommodate the forward end of the speed tubes). This leaves about a 40" gap between the inside edge of the bunks athwartships.

- should the bunks be positioned inside the speed tubes as I have?
- is 40" too wide to support a SIB over the long term?
- should I consider adding a second set of 2x4" bunks close to the keel to better support the hull?
- would the additional friction of another pair of bunks (albeit narrower 2x4) impede the ability to winch the boat up onto the bunks?

I suppose some of these questions are conjecture because until I put the trailer in the water I won't know how high the boat floats relative to the bunks. Still any insight into this would be greatly appreciated. Thanks RIBnetters
Phil

jonp · Yesterday, 20:49

Any boat I ever buy, I set the trailer up so I can quickly and easily drive the boat onto the trailer. Setting up the v bunks with plastic bunks that line the boat to the centre makes life so easy. Most of the ramps I use will have several hundred boats launch and retrieve in a day, so most people have similar setups to mine. The tubes shouldn't come in contact with anything on the trailer.
I also opt for marine grade aluminium c section trailers these days as galvanised box section trailers have limited life in comparison and require more maintenance.