Trailer bunk Shimming

[mnpracing]

I want to shim my trailer bunks to get additional prop clearance. What are some ideas on how to get 1-2" additional clearance? I've tossed around using fender washers (probably need too many), an additional piece of 2x6 at the mounting points, or just doubling up the 2x6's for the entire length of each bunk. Also if I do this to the front mount of the front bunk as well, I'm guessing that I would have issues with the bow stop / u-bolt mating.

Thanks in advance for any help and ideas.

[you da man]

Wow, that's alot of shimming. I've seen/heard people needing an half inch but 2 inches? What prop you going to justify the need of that much addition clearance?

[mnpracing]

I haven't picked one out yet, but currently I have less that 3/8" clearance between the lowest point on the prop and the metal strip that runs underneath it (when on the trailer). It's the stock prop on an 06 OBV.

So maybe a more realistic amount would be shimming 1"?

Thanks

[you da man]

1" is definately more reasonable. I may shim mine up when I go to the Acme 1235 or the OJ Fusion prop. There are members on here that have gone from stock props to the Acme 1235 and don't have clearance issues so they say but they also have LSV's and XLV's

[MartinCaron]

What's the normal clearance ?

[mnpracing]

Have you thought about how to shim them? I'm not sure what to use to do it.

[you da man]

What's the normal clearance ?

He said about 3/8"

[Razzman]

Remember this, the bunks do not sit flat but angle in towards the centerline of the boat/trailer. As the trailer and therefore the bunks are designed for that boat and the bunks are designed to sit in the pockets under the hull, shimming them (especially 2") will move them even further inboard and i'll bet you 100 to none that your boat will no longer fit correctly on your trailer and not just the bow stop. I know that on my '07 LSV when centered on the trailer there's less than 1/2" clearance on each side of the bunks and hull.

[Razzman]

Oh yeah, mine is about 3/8" to 1/2" as well. In fact if you search the prop test threads Ed started you'll find his measurements for that and a full discussion on the issue.

[mnpracing]

Razzman, so what does a person do if you want to run a larger diameter prop? Wouldn't shimming work as long as you maintained the same distance between bunks (if the lift is too drastic you may need to replace the boards and drill the new boards slightly offset from the original to get the same spacing)?

If shimming would work (let's say I just need 3/4" to 1"), what would you use as shims?

[Razzman]

Razzman, so what does a person do if you want to run a larger diameter prop? Wouldn't shimming work as long as you maintained the same distance between bunks (if the lift is too drastic you may need to replace the boards and drill the new boards slightly offset from the original to get the same spacing)?

If shimming would work (let's say I just need 3/4" to 1"), what would you use as shims?

First question is what is the prop diameter? What is your current diameter?

I wouldn't shim more than 3/4" and if i was to i'd use synthetic material similar to HDPE or Trex deck material the same size as the bracket, i sure wouldn't use washers or such as that will only increase the pressure points and cause bowing of the bunk boards.

[ssmith]

Here you go...

Maybe this will help

http://i175.photobucket.com/albums/w126/scotties2006/Boating/SU1HMDAwMDgtMjAxMDA1MDctMTgyMS5qcGc.jpg

http://i175.photobucket.com/albums/w126/scotties2006/Boating/SU1HMDAwMDUtMjAxMDA1MDctMTc0MS5q-1.jpg

[Razzman]

And there's your answer in black & white :p 3/8" HDPE will work for the task.

[sailing217]

SSsmith: Please post where I can get that Supra Shim Kit?!?!

Put it this way, my dealer has never seen a trailer like mine with NO CLEARANCE, brand new from boatmate made for my Centurion. Yes my prop will touch the trailer by maybe 1mm unless I crank the bow stop as tight as I can. If I left it snug but not cranked, my prop can touch. I need a shim kit.

Will do this Fall when it's slow and leave the boat at the dock (opposite the ramp side) while I re-shim in the parking lot. Might re-carpet while there too.

THX. Great thread

[Poison]

Sailing, did you ever get ahold of your shim kit? If so, did you order it from Boatmate or where? Thanks

[ssmith]

SSsmith: Please post where I can get that Supra Shim Kit?!?!


Sorry for the late reply.

I got the kit from Jerry at Boatmate. You can email him: [email protected]

Ask him for the shim kit and include your trailer serial number and your address in the email. He should take care of the rest.

Good luck.