Roller > bunk conversion, strength of the bunks?

jgoeden

Petty Officer 3rd Class
Joined
Aug 14, 2010
Messages
78
Hey guys, I have a roller trailer and I always hated the rollers and never trusted them (don't think they are configured properly for the boat). Well I noticed last fall that the middle cross member of the trailer was rusted through and broken. So I bought a new cross member and got it installed.

Then I started toying with the idea of going to bunks. It just seems like they have more support and better boat weight distribution (if you know what I'm trying to say).

IMG_20110406_092911.jpg

So, the first picture (above) is of the new installed bunk. Now I'm going to be putting on a pair of middle bunks, but where should I do them? I'm not good with terminology but I put the first pair near the outside near the strakes (???). Should I put the next bunk (all 2x6's) pretty much down the center with the keel (???) or should I spread them out maybe with a foot or two in between?

IMG_20110408_150307.jpg
IMG_20110408_150246.jpg

I thought I read somewhere to place them under the stringers, how can I find where those are? Knock on the fiberglass like finding studs in walls?

Also, once I get all the bunks all, will they be strong enough to completely support the boat since they aren't factory welded on there? I'll still have a roller on the crossmembers in case the keel wants to hit the member when loading, but it won't be for support, it'll just be for damage protection.

Sorry this is so long, I'm long-winded. I hope at least a little of this makes sense. My main worry is strength. Am I over worrying? Are my bunks way stronger than I give them credit for?
 

444

Senior Chief Petty Officer
Joined
Jul 16, 2010
Messages
704
Re: Roller > bunk conversion, strength of the bunks?

I would put them where you planned the blue ones for. Bolted on securely with lock nuts should perform just as well as welded.
 

infideltarget

Master Chief Petty Officer
Joined
Aug 30, 2010
Messages
802
Re: Roller > bunk conversion, strength of the bunks?

Here is a pic of my trailer and the bunk positions.

Hope this helps.
 

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Evinbuck

Seaman
Joined
Oct 12, 2010
Messages
70
Re: Roller > bunk conversion, strength of the bunks?

I second the opinion of the blue position you indicated. Also, I would assure the bunk was flush with the rear of the transom for support. Without doing that you can actually get a cup in the hull in front of the transom or cracking
 

Pez Vela

Chief Petty Officer
Joined
Dec 4, 2004
Messages
504
Re: Roller > bunk conversion, strength of the bunks?

I would put them where you planned the blue ones ...

Agreed ... and the next ones in the "blue" position should be considerably longer than the first bunks you've installed. It also appears that you have installed the wrong mounting brackets (roller bunk) in the wrong position (sideways to the way bunk brackets are meant to be installed) and have attached them incorrectly as well (fastened to the frame instead of the cross member). They way you've done it, the brackets are not supporting the wood properly, and I wouldn't trust it that way over time. I'd check into brackets which are designed for bunk boards and how to mount them properly.
 

jgoeden

Petty Officer 3rd Class
Joined
Aug 14, 2010
Messages
78
Re: Roller > bunk conversion, strength of the bunks?

Thank you all for your reply. I'm not sure how I have the wrong brackets, I ordered 12" adjustable bunk brackets from a marina. Are they really not good on the frame. You'd think they would be stronger directly on the frame. Anyways, if they are going to fall off, I guess I can switch them to the cross members. But I'm pretty sure they are bunk brackets designed for wood applications. Thanks for all the advice though, I'll install the new ones in the blue location. They are also 8' long, should I go to 10'? I've already bought the 8 footers though and really want to use them.

Also please tell me how they are not supporting the wood properly. The brackets are fastened down with 1/2" u-bolts to the frame and the angle brackets are bolted to the wood with 1/2" lag bolts if I'm not mistaken.
 

infideltarget

Master Chief Petty Officer
Joined
Aug 30, 2010
Messages
802
Re: Roller > bunk conversion, strength of the bunks?

Thank you all for your reply. I'm not sure how I have the wrong brackets, I ordered 12" adjustable bunk brackets from a marina. Are they really not good on the frame. You'd think they would be stronger directly on the frame. Anyways, if they are going to fall off, I guess I can switch them to the cross members. But I'm pretty sure they are bunk brackets designed for wood applications. Thanks for all the advice though, I'll install the new ones in the blue location. They are also 8' long, should I go to 10'? I've already bought the 8 footers though and really want to use them.

Also please tell me how they are not supporting the wood properly. The brackets are fastened down with 1/2" u-bolts to the frame and the angle brackets are bolted to the wood with 1/2" lag bolts if I'm not mistaken.

close up pics would help, but your description sounds right. 8' will be fine for your boat length.
 

jgoeden

Petty Officer 3rd Class
Joined
Aug 14, 2010
Messages
78
Re: Roller > bunk conversion, strength of the bunks?

Thanks man, I'll try to get some more pics as soon as possible. I'm working nights for the next 3 nights so it might be early next week, but I'll definitely get some more pics.
 

Pez Vela

Chief Petty Officer
Joined
Dec 4, 2004
Messages
504
Re: Roller > bunk conversion, strength of the bunks?

I compared your brackets to these ... http://www.blackbearsportinggoods.com/ProductDetails.asp?ProductCode=ELLCESM10003GA&click=12 ... and they appeared to be the same, and made specifically for rollers. What I meant by saying they were not supporting the wood properly has to do with twisting the mounts 90? so that the bracket's mounting plate is centered across the bunk, not running lengthwise along one side of it. I'd check into this further just to be safe.
 
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