Convert regular trailer to inboard trailer

[jlcalbre]

In looking around for a new trailer for my inboard ski boat, i talked to someone who says he can take a regular boat trailer and convert it for use on an inboard by basically raising the bunks to provide the additional clearance for the drive shaft. Supposedly, they do this on used trailers, which keeps the cost down. Seems like this would raise the center of gravity making the trailer a little unstable, as well as making it difficult to load boat. Anyone heard of this? Any opinions on whether this is a good or bad idea? Thanks.

 

[tashasdaddy]

Re: Convert regular trailer to inboard trailer

you are 100% correct. horrible set up. get a proper trailer, that has the notch for the drive shaft, and prop. it may cost more, but you will never be sorry. like this. http://www.boatingbay.com/listings/INBOARD-BOAT-TRAILERS-FOR-SALE-5070.html

 

[jaxnjil]

Re: Convert regular trailer to inboard trailer

what TD says + you dont want to raise the bunks as you will need to back farther down in the water just to float your boat.

 

[reelfishin]

Re: Convert regular trailer to inboard trailer

Some trailers are designed with the option of removing a rear cross member section to allow clearance for a prop and shaft. My older Sealine trailers are built that way. The rear of the frame is boxed in with only a light section of crossmember closing in the rear box, it's a little more than tacked in place and would easily come out if I needed to convert it to inboard use.

Look around, so trailer designs lend themselves better to this modification than others do. Not all can be modified and in those cases it's best to find a better suited trailer.

 

[oops!]

Re: Convert regular trailer to inboard trailer

all above very true.......my old steel trailer has raised bunks.....i hate it...i have to go really deep to float off.....

if you were to raise yours with out dropping the rear cross member or welding a new rear section on your trailer.....you would be at least 18 inches off the frame of the trailer.......good luck with a rig like that !

 

[salty87]

Re: Convert regular trailer to inboard trailer

i agree with these fellas

the running gear is way too expensive to hold your breath everytime you load/unload from the trailer.

seems the cost of the i/o trailer plus proper mod's would cost more than going with an inboard trailer.

 

[QC]

Re: Convert regular trailer to inboard trailer

Well . . . I am actually doing this now . . . Buuuut I am cutting out the rear crossmember center section and then welding in a lower "drop" to it. I will have to raise the rear bunk mounts about 2", but that is typical to an inboard trailer. Remember, with a flat bottom and the weight forward (mid-engine, direct drive) they float off differently than a deep V with all of the weight in the stern anyway. I agree with the others though, that simply raising the bunks to achieve ALL of the clearance is the wrong way to do it.

This is a typical example:

 

[J. Mark]

Re: Convert regular trailer to inboard trailer

I am planning the same conversion for my trailer (Which is galvanized)

We are going to weld the hoop on with a gusset and then cut the crossmember and cap the ends.

Would like to see how this worked out for you.

 

[jfw432]

Re: Convert regular trailer to inboard trailer

I'm reviving this thread to see how many people have actually just raised their bunks to accomodate an inboard boat. I'm looking at doing this to a boat lift so COG while driving and backing down a ramp aren't an issue.

How do you guys raise the bunks? Do you just add additional boards or do you get totally different mounts?

 

[gozierdt]

Re: Convert regular trailer to inboard trailer

I've done what QC did to two different trailers that were originally I/O or Outboard boat trailers. I cut the rear crossmember and welded in a dropped center section, plus added another dropped crossmember about 2 1/2 feet forward of the rear crossmember (this one was only dropped about 1/2 the amount of the rear one). Then I welded a small U-beam in between the center of the forward dropped crossmember and the rear dropped crossmember. This provides protection for the prop if anything gets up under the back- like if the wheels dropped off a curb. Then you still need to raise the bunks up a couple of inches. You can't drop the rear crossmember far enough to allow the prop to clear with the original bunk height. The dropped section would drag all the time coming off parking lots or curbs.

You'll also need to plan on moving the axles forward more under the engine- otherwise the tongue weight will be way too high, because the CG of the inboard boat is forward of an I/O boat of similar length.

Be really careful welding on a galvanized trailer- you need to grind the galvanizing back away from the weld zone. The fumes are very toxic if you weld directly over the zinc.

 

[QC]

Re: Convert regular trailer to inboard trailer

I actually did not do that trailer, it was an example. FWIW, I found a great deal right after that on an inboard trailer and sold the other, so I've got nothing to add . . . :redface: