Converting roller to bunks, worth the trouble?

[ricohman]

I just bought an older 16 ft aluminum Starcraft. It has a roller trailer. All the rollers are in good shape, but decades of riding around have left bare spots and shallow dents in the hull.
I've used both types of trailers before and I actually liked being able to stay dry while launching or retrieving my boat. But if hull damage is going to get worse I'd rather get my feet wet with a bunk trailer.
How long would it take the average guy to convert to bunks? I'd like to do this at home with access to all my tools.
If I lift up the boat and block it, can I leave the trailer in position to install the bunks? Or is this to dangerous?

 

[jimmbo]

What brand is the trailer? Some models of some brands were could be equipped with rollers or bunks. Easier to convert. Maybe more rollers could be added to you trailer to spread the weight of the boat over more contacts

Picture of said trailer will reveal much info

 

[ricohman]

What brand is the trailer? Some models of some brands were could be equipped with rollers or bunks. Easier to convert. Maybe more rollers could be added to you trailer to spread the weight of the boat over more contacts

Picture of said trailer will reveal much info

The trailer is a 1984 Univision. I am thinking about removing the rollers and bolting bunks onto the factory supports.
That would give me 8 short bunks in the same position as the original rollers.

 

[ricohman]

Here is the real problem. This trailer was equipped with only one set of rollers up front. And it has marked the hull and left shallow dents. The boat was positioned to far rearward when I got it and it was probably bouncing around somewhat as the trailer has virtually no tongue weight.


The rear has two sets of rollers on each side.

 

[thumpar]

Normally a bunk trailer only has 2 or 4 bunk. Since it looks like you have fixed the position I would probably leave it. It would take some work to convert.

 

[ricohman]

Perhaps adding a forward keel roller would help take some pressure off the hull?

 

[jimmbo]

If your gonna put more rollers on the trailer, put them where they do the most good at the stern. You could still move the boat forward an inch or so. The back rollers should be right under the transom

 

[gm280]

If you make your decision to replace the rollers, I can see two wide carpeted bunks working very well. Not only would it spread the load of the hull over longer areas, it would allow you to position the boat exactly where it need to be for proper tongue weight easily. But it is your decision. JMHO!

 

[airshot]

From your pics it appears that you have to few rollers or you need to add a couple keel rollers as well as pull the boat forward and inch or two. Roller trailers are good as long as everything is properly set up and you have the proper number and placement of the rollers. I have a 1983 22' StarCraft aluminum hull that has sat on its roller trailer for 33 years and does not have the issues you are talking about, but it is properly setup and has plenty of rollers as well as a couple keel rollers.
Bunks can offer a better weight distribution, no one can argue that but launching and retrieving can be more difficult. I have had both types of trailers over the years and have had no issues with either one but I do like the roller trailer for ease of launch and retrieve and so much easier to replace a roller than to re-carpet bunks.

 

[thumpar]

airshot is right on about the difference. I have a bunk trailer now but had a roller before. The bunks stick the boat on so it is harder to get off the trailer and back on. I like the solidness of the bunk trailer over the roller. With the bunk trailer it is hard to get the boat to center on the trailer. With the roller I could just crank the boat up. With a bunk you have to either power load or get the trailer deep in the water. I extended the tongue of my trailer 3' so I could get it deeper because I had to have the tow rig almost to the bumper deep to launch/retrieve.

 

[ricohman]

Well, I bought a single keel roller to add up front. But the clearance is limited. I suppose this old boat has been sitting on this trailer improperly for 30 some years.
Some of the lakes I am planning on going to up north have nothing for a launch. I have seen guys get their trucks stuck trying to back in deep enough. Rollers are king at some of these lakes. Unless you want to drive around to the other side which takes a couple hours.
If I could convert this easily I would. I guess I will work with what I have.

 

[Capt'n Caution]

Ricohman:
This is a fine example of a good quality, tough old boat that was built to survive. I have driven Saskatchewan back roads, and they can be darn rough. Unfortunately, it does show what can happen to an alu boat on rollers. You did not mention leaky rivets, but I would be surprised if the ones close to the rollers were not stretched enough to weep. I agree completely with your desire for easier unloading at shallow ramps. I have a 6' piece of 2x2 x 1/8" alu square tube with a trailer ball on one end which fits the receiver to get a few more feet of reach at shallow ramps. But it would be a lot simpler and easier to roll the boat off. I have only had bunks for trailering aluminum boats, and I use an unloader system with the winch to assist me. You could convert to bunks, but you might need to remove the boat to get the bunks in properly, and at least level to start with.Then you could fit the bunks once the boat was back on. That probably means the motor would have to come off first. Clear 2x8 bunks extending aft of the transom a couple of inches could work. You can get adjustable bunk supports that fit what looks to me as rectangular steel tubing crossbeams. There are some trailer manufacturers that do mail order of these parts. Whatever you do, you will have to reduce the point loading on the alu. I sure that you are aware that 10 to 15% of the gross weight should be on the ball. Too much weight at the rear can cause severe fishtailing at highway speeds. The current tie down straps at the transom are only about 20% effective at holding the boat down. The major force they exert is to hold the boat forward. This allows the boat to rise up some at every bump. The better way is to run a strap around the boat from the trailer frame, with the pull as vertical as possible. This will reduce the amount that the boat will bounce. Lots of work ahead, I'm afraid!

 

[ricohman]

Ricohman:
This is a fine example of a good quality, tough old boat that was built to survive. I have driven Saskatchewan back roads, and they can be darn rough. Unfortunately, it does show what can happen to an alu boat on rollers. You did not mention leaky rivets, but I would be surprised if the ones close to the rollers were not stretched enough to weep. I agree completely with your desire for easier unloading at shallow ramps. I have a 6' piece of 2x2 x 1/8" alu square tube with a trailer ball on one end which fits the receiver to get a few more feet of reach at shallow ramps. But it would be a lot simpler and easier to roll the boat off. I have only had bunks for trailering aluminum boats, and I use an unloader system with the winch to assist me. You could convert to bunks, but you might need to remove the boat to get the bunks in properly, and at least level to start with.Then you could fit the bunks once the boat was back on. That probably means the motor would have to come off first. Clear 2x8 bunks extending aft of the transom a couple of inches could work. You can get adjustable bunk supports that fit what looks to me as rectangular steel tubing crossbeams. There are some trailer manufacturers that do mail order of these parts. Whatever you do, you will have to reduce the point loading on the alu. I sure that you are aware that 10 to 15% of the gross weight should be on the ball. Too much weight at the rear can cause severe fishtailing at highway speeds. The current tie down straps at the transom are only about 20% effective at holding the boat down. The major force they exert is to hold the boat forward. This allows the boat to rise up some at every bump. The better way is to run a strap around the boat from the trailer frame, with the pull as vertical as possible. This will reduce the amount that the boat will bounce. Lots of work ahead, I'm afraid!

You know, I actually had two missing rivets. The heads bust off. I've since stopped the water leaking in but I am now going to keep my eye open for a bunk trailer project. This way I can rebuild it and set it up without losing any boating time. And I will take both trailers to the launch on a nice fall day when its quiet and swap the boat onto the other trailer as many times as it takes to get the bunks right.
But I will keep the roller trailer. I know of a few lakes up north where its darn near impossible to get a bunk trailer in.

 

[Lou C]

I would look into adding a pair of articulating roller bars with at least 4 rollers each where you have the dents. On my 20' 'glass boat I have 24 rollers ant it loads pretty easy....I did add a longer tongue was well...

 

[ricohman]

I would look into adding a pair of articulating roller bars with at least 4 rollers each where you have the dents. On my 20' 'glass boat I have 24 rollers ant it loads pretty easy....I did add a longer tongue was well...

I never thought of this. Increasing the number of rollers would certainly help. And since I will keep this trailer for the rough northern roads, I am going to look into this.
Thanks for the tip!

 

[Capt'n Caution]

No Title

Ricohman:
Here's a photo which appears to be a conversion from rollers to bunks. I do not know what boat was on it, but I suspect it is used in salt water. You can see how the forward bunks are curved. I presume this is to conform to the hull in this area, but how could you get the exact curve. A flat bunk might contact in just one spot. Maybe a combination of aft bunks with forward rollers and a forward keel roller might work. Thought you might be interested.

 

[thumpar]

That is an interesting setup. Normally a bunk trailer is setup with 2 long bunks or 2 long bunk and 2 shorter bunk. They should be a solid setup. Those like they pivot like a roller trailer would.

For the curve you just put the boat on it. That is why the boards are longer. The wood will conform.

 

[fibersport]

You could replace the rear rollers with bunks which will help support the boat and add a bow roller as previously mentioned. EZ Loader trailers were primarily roller trailers but you could also get bunks instead, a pretty simple job to install them, all you would need is a clamp type arrangement on the bunks to connect to the arms that the rollers mount to now. Also, consider that the stern will usually float a bit when launching depending on the ramp, however no matter the ramp, once the carpet gets wet will will slide easier. I coat my carpeting with silicone spray, it really helps.

 

[thumpar]

I have had both. Bunks don't slide at all compared to rollers. The solidness of bunks is nice. There is more maintenance with bunks though.

 

[ricohman]

Ricohman:
Here's a photo which appears to be a conversion from rollers to bunks. I do not know what boat was on it, but I suspect it is used in salt water. You can see how the forward bunks are curved. I presume this is to conform to the hull in this area, but how could you get the exact curve. A flat bunk might contact in just one spot. Maybe a combination of aft bunks with forward rollers and a forward keel roller might work. Thought you might be interested.

Yes, that is exactly what I was thinking. Looks to be sturdy enough.