roller damage

[jeremy5780]

Have a new to me dual axle trailer for my 20 ft mako I have two bunks and three rollers one roller in the back one in the middle and one of front. I noticed that the front roller is not rolling and with the boat going on and off it has wore a groove in the roller. It's a new roller and with the boat off it spins freely. My question is should I just remove the roller completly? It's obvious there is to much weight on the roller. what do you think?

 

[bonz_d]

Re: roller damage

1st thought for me is there room to add another roller to spread the weight?

 

[1980Coronado]

Re: roller damage

Shouldn't the boat be sitting on the bunks? The weight of the boat should be carried by the bunks...can you raise the bunks to take some load off the roller?

 

[tpenfield]

Re: roller damage

what 1980 said and add another roller in the front, so it has the support of 2 rollers.

 

[bonz_d]

Re: roller damage

My question is should I just remove the roller completly? It's obvious there is to much weight on the roller. what do you think?

Go ahead and remove the roller and then let us know how it works out.

Then think about your own statement. "It's obvious there is to much weight on the roller." If you remove that roller what's going to happen? Evidently there is more weight in the bow of that boat than the bunks can support unless that roller is positioned too high to begin with.. Which I kind of doubt.

How long are the bunks? Is the Keel touching all three rollers? Only the front two, evenly? Or just the front bow roller?

"Shouldn't the boat be sitting on the bunks? The weight of the boat should be carried by the bunks...can you raise the bunks to take some load off the roller?"

Not if it is a Keel Roller with Bunks type trailer.

 

[1980Coronado]

Re: roller damage

Most of the weight of the boat should be carried by the bunks, even with keel rollers. You do not want a majority of the weight on the keel creating a point load bouncing down the road. The roller can be in contact with the keel, but it should not be carrying a majority of the load, that's what the bunks are for.

 

[bonz_d]

Re: roller damage

The roller can be in contact with the keel, but it should not be carrying a majority of the load, that's what the bunks are for.

Explain how you are going to do this if and when the bunks are only half the length of the boat or less as with a keel roller trailer? Can't happen. They are designed to support the keel.

 

[ezmobee]

Re: roller damage

Oh man, here we go again with that arguement :facepalm:

There are two distinct camps in this battle. I'm in the "bunks should be raised to support the majority of the weight" camp. bonz_d, yes the bunks are only half the boat but it's the half with the vast majority of the weight.

 

[1980Coronado]

Re: roller damage

Explain how you are going to do this if and when the bunks are only half the length of the boat or less as with a keel roller trailer? Can't happen. They are designed to support the keel.

My boat is 21'-10"....the bunks on my Shore Station lift are 10' long and the keel does not touch the lift cross beams...this is more than adequate support for the hull.....all of the weight (3600#) is being carried by (2) 2 x 6 x 10 carpeted bunks. Center rollers are there to protect the keel during loading, they are not designed to carry a majority of the load when traveling down the road. If the front roller on the OP's trailer is having a groove wore into it, it's carrying too much weight.....lower the roller or raise the bunks a tad...it's not going to take much to solve the problem.

http://www.stoutusa.com/images/DSCF00111.JPG

 

[bonz_d]

Re: roller damage

Oh man, here we go again with that arguement :facepalm:

There are two distinct camps in this battle. I'm in the "bunks should be raised to support the majority of the weight" camp. bonz_d, yes the bunks are only half the boat but it's the half with the vast majority of the weight.

Half is supported, it has the most weight. Another half is not supported. So if you balanced this arrangement, car boat, airplaine whatever, where has the axsis of gravity moved to? Say as in 1980's 22' length that is supported from one end to 10' into the center. Is this balanced? Will there be more weight 2' from the bow than 6' from the bow? Try it and let me know.

 

[bonz_d]

Re: roller damage

My boat is 21'-10"....the bunks on my Shore Station lift are 10' long and the keel does not touch the lift cross beams...http://www.stoutusa.com/images/DSCF00111.JPG

So what does this prove? A neighbor next door had a 18' inboard ChrisCraft that would hang in a boathouse by 2 chain lifts. One in a hook on the bow deck and one in a hook on the stern deck. No slings.

 

[1980Coronado]

Re: roller damage

So what does this prove? A neighbor next door had a 18' inboard ChrisCraft that would hang in a boathouse by 2 chain lifts. One in a hook on the bow deck and one in a hook on the stern deck. No slings.

It shows that you don't want a point load on the cross beams and the keel...the boat is completely off of the keel and cross beams intentionally. Now, if a stationary lift is designed intentionally to keep the point load off of the keel and cross beams, why would you want a point load on the keel and cross members of the trailer which is dynamic? Have you ever noticed at the marina when they put a boat on a dolly to roll it around that the keel does not sit on the dolly? Why?

The Center of Gravity of the boat doesn't change when it's on the trailer...you adjust your bunks on the trailer to move the boat forward or backward to achieve the appropriate tongue weight.

My Coronado can be hung by Davits in the same way the Chris Craft can....they were designed that way.

No roller supporting the bow

 

[bonz_d]

Re: roller damage

The Center of Gravity of the boat doesn't change when it's on the trailer...you adjust your bunks on the trailer to move the boat forward or backward to achieve the appropriate tongue weight.

You are correct the CG of the load does not change unless the load itself is altered. What changes is the fulcrum point! The fulcrum point could be and usually is the axle of the whole load. There is also a secondary fulcrum point involved here which is the bottom of the boat and the bunks. If you will notice the picture you posted of your boat the bunks extend past the center of gravity which will move the fulcrum point to the stern. The same is true of all the pictures of the boats on the lifts in the website you posted. The bunks extend well past the CG. On trailers where the bunks do not come to the CG of the boat the fulcrum point becomes the end of the bunk. And the further the fulcrum point moves rearward the CG moves forward placing more downward force on the forward end. It's call physics.

Whether you accept it, like it or not there are a very good number of trailers out in the world, new and used were the bunks do not extend past the CG. Many of them the bunks do not even extend past the axle. Which is why they use so many keel rollers from the center forward. I did not design them but they are there just the same.

Now I have not seen this trailer and I assume neither have you so neither of us can judge what the trailer looks like or how long the bunks are. The only fact known is that the front roller is being crushed. Caused by too much weight upon it. This can only be the result of one of 2 things. 1, the roller is to high and is lifting the bow off the bunks or 2, the bunks are too short of the CG causing more weight to be placed forward.

Also, I personally have never moved a set of bunks to change the CG on a trailer. I personally just move the boats position on the trailer or move the axle. I also do not have any personal stake in which type of trailer some one else uses. That is pure personal preference. As I also do not believe any one type trailer is better or worse than the other I will not argue some one elses preference.

 

[ezmobee]

Re: roller damage

The only fact known is that the front roller is being crushed. Caused by too much weight upon it. This can only be the result of one of 2 things. 1, the roller is to high and is lifting the bow off the bunks or 2, the bunks are too short of the CG causing more weight to be placed forward.

I think we can all agree with this.

 

[1980Coronado]

Re: roller damage

Op's trailer has three keel rollers, the trailer in my post has three keel rollers....he has two bunks I have four. Both are tandem axle trailers, both boats are in the 20'-22' range......his trailer probably looks very similar to the picture I posted. I'm making an assumption. I'm also assuming the trailer and bunks are appropriate for the boat. Pictures would be nice. Some bunks can be adjusted a small amount so that if you have to move the boat forward and don't want the bunks sticking out the back, you can move them a few inches.....for larger adjustments, you have to move the axles.

We know there is too much weight on the front roller and my advice was to move the bunk up to take some pressure off the keel roller in the front. It doesn't take long to try, and it doesn't cost a penny.

 

[oops!]

Re: roller damage

this is the first time i have seen the debate that EZ is referring to.

.....im getting a kick out of the responses....

there is some serious over thinking going on here.

its all about the hull support for the specific hull..and tongue weight. the tongue weight is determined by the axel placement for any given boat.

to the OP......either move the bunks forward a tad or drop the front roller a smidge........without pics it would be hard to tell....im guessing a bit of both.
you want the center rollers to guide the boat into the correct position. that means they must roll easily.

 

[bonz_d]

Re: roller damage

this is the first time i have seen the debate that EZ is referring to.

.....im getting a kick out of the responses....

there is some serious over thinking going on here.

oops I'm suprised, I've wittnessed this debate before on this forum and because of it I've learned a few things and have even changed my opinion some because of it.

Sorry but I get upset when some seem to think all trailers with bunks are the same and should be used and set-up the same.. Again sorry but they are not all the same. Some have rollers that are designed to guide and protect the hull from striking the frame members, others have no rollers at all. Then there are Keel roller trailers which have very short bunks. These trailers were designed to support the hull by the keel, not the bunks. Case in point, the keel roller tilt trailer that I just sold. It had 5 keel rollers and 4' bunks. The bunks ended just before the axle. The whole idea is so that when the trailer is tilted the boat rolls easily off. Supported by the keel rollers. So if most or all of the weight was on the bunks when tilted it would never slide off w/o a lot of effort. Same when trying to load it in a tilted position. Would be next to impossible!

On that trailer I used the tilt function so often that I was replacing the 1st roller every 2 years because it would take such a beating from loading. The ramp next to my house is so shallow that by the time the boat is on the trailer and tilted down in it's running position the lower unit of my outboard would be completely out of the water. BTW I have used all 3 of these types of trailers and now have an all roller trailer. My opinion is that none is any better than the other as long as it fits the boat and is set up correctly.

 

[oops!]

Re: roller damage

i dont spend a lot of time in this forum......mostly in general and the restoration.....so i havent seen this issue much.

it is very true that there are many different typed of trailers.....each must be set up correctly for each boat that they will carry.

there are "job specific" trailers......these are for very unusual circumstances...... a person tan take there trailer and (generally speaking) set it up for there common launch point.

but each trailer MUST support the hull properly.....or the trailer will damage the boat. for example......a roller trailer can and will damage a hull if the rollers are not in the correct spots under the cross frames........like wize....a trailer with center rollers can and will damage a boat that has no center stringer, if the rollers are too high and the bulk of the weight is on the keel, with the bunks just to stabilize the boat.

loading and unloading issues are owner specific.....some power load.....some float on/off....some winch.....(mostly with rollers) the owners habits must change with the type of trailer he or she has.

but the main thing.....is that the boat is properly supported......supported across the frames or under the stringers. that the tounge weight is correct for the vehicle (as well as the axles being in the correct position).

im personally not a big fan of roller trailers with heaver boats....due to the chances of the hull being incorrectly supported. the lighter the boat....and the more foam in the hull, makes rollers ok......but a heavy boat with little foam and the glass will stress on longer trips over bumpy roads.

even tho my trailer is a total POS...with everything wrong with it......even extended the thing by 5 feet......my boat is correctly supported......and if the bearings wernt toast...i would have no issues driving the rig down a washboard gravel road for 10 hours.....the boat must be supported correctly.

 

[ezmobee]

Re: roller damage

Oops, I've seen your trailer. You should probably stay in the resto forum

 

[bonz_d]

Re: roller damage

Now all we need is to hear from the original poster to this thread! What happened? Is it resolved?