Is a single axle enough for a 21' Bowrider?

[joleda]

I picked up a '86 capri 2150 and it came with a Calkin single axle trailer with surge brakes. Is this enough trailer to handle this boat? I guess it came with the boat when it was new in '86. But the laws have changed a lot in 24 years. I know most single axles only have a 3000 lb rating. The manufacturers tag is faded and I have know idea what it is rated at.
Any advice would be appreciated.
Thanks,
Dave

[Lindeman23]

I have a 97 Four Winns 205 Sundowner. It came with a FW matching single axel trailer from the factory, boat is about 4500lbs. You should be fine, even though having a tandem would be nicer.

[Lou C]

It depends on how it was set up. If it has a 6 lug axle with 15 in rims then you may have a 5200 lb capacity axle and that would be adqequate...if it's a 5 lug axle with 14 in rims that would limit it to 3500 including the trailer which would not be enough capacity...

[Chris-R]

It depends on how it was set up. If it has a 6 lug axle with 15 in rims then you may have a 5200 lb capacity axle and that would be adqequate...if it's a 5 lug axle with 14 in rims that would limit it to 3500 including the trailer which would not be enough capacity...

Lou C is completely right. It's all about the axle and tires. If you have 5 lug wheels with 14 inch tires, you are probably not good but 6 lug wheels with 15 inch tires typically is fine but check the load range on the tires.

[mike343]

The guys are right about load ratings, but if you plan to tow at some distance, a tandem trailer will be easier on the driver. Single axle trailers just aren't as stable as tandems. We put a tandem trailer under a 2500 lb rig (after an accident cause by a blowout). hard to describe the difference.

[proaudioguy]

I've been considering adding an axle for this reason. I have a single torsion axle with good radials. I towed it to the keys and back, but wasn't super happy about the possible outcome if I had a blow out. It tows great and is easy to maneuver though. I was thinking of sliding the axle then adding a second so the cog was the same, but spread over both.

[jacknbella]

If you ever get to experience a blow-out at highway speeds like I have, a tandem axle will surely save your rig (and keep you from needing to change your underwear). Go with the 2nd axle for a peace of mind.

[Lou C]

I don't tow at highway speeds so a single is OK for me and they are easier to move around in narrow driveway I have to park it in, and less maintenance. But if I did do a lot of highway driving for sure I'd had a tandem, the safety benefits are real, and it certainly is not overkill on a 21 foot boat that probably weighs in at around 4000 lbs....

[109jb]

According to the specs for a 1986 Capri 2150 found here on I-boats, the boat dry weight is 2495 pounds. To that you have to add fuel weight and anything else in the boat including any excess weight the boat might have due to waterlogged foam, and the trailer weight.

Given that, a 3500 pound capacity single axle trailer "should" be OK. Your best bet would be to take the trailer to a truck scale and have it weighed. If the trailer is a 3000 pound capacity, I would either put a second axle under it or a larger capacity single axle.

[rwidman]

Adding an axle or replacing the existing axle on a boat trailer does not increase the capacity. The manufacturer takes into account the strength of the frame and crossmembers as well as the bunks or rollers and actuator when determining capacity.

If your boat exceeds the capacity of the trailer, you should buy a bigger trailer.

The most common trailer axles have a 3500 lb capacity. These are the ones that use five bolt wheels.

[bruceb58]

Adding a second axle would be a way to go in my opinion. I know Rwidman won't agree(of course he never does) but how can adding a second axle to an existing one axle trailer make it any worse? Its still the same load! Its not like you are putting on a bigger boat on than what you have. You are just adding some safety margin.

[rwidman]

Adding a second axle would be a way to go in my opinion. I know Rwidman won't agree(of course he never does)........

I agree with posts I believe are good advice and I don't agree with posts that I believe are not good advice. Isn't that what you do? Isn't that what everyone does?

[cribber]

Sounds like your trailer is likely adequate for your boat. To be sure do your typical setup for a day of fun and take it to the scales and have it weighed. If your less than 3500 pounds your golden. My boat is a 2008 Glastron GT-185 and dry weight is 2315 lbs riding on a 3100 lb capacity rated EZ-Loader. The GAWR is rated at 3750 with 14" 5 lug tires.

[NYBo]

Its still the same load! Its not like you are putting on a bigger boat on than what you have. You are just adding some safety margin.

Well, you ARE adding the weight of the second axle, two more tires and wheels, etc.

[bruceb58]

Well, you ARE adding the weight of the second axle, two more tires and wheels, etc.

The frame of the trailer happens to ride ON the axle so no extra load is added to the frame. In fact it helps the frame since now the load is supported at an extra point.

[Lou C]

I actually looked into doing that, adding a tandem spring mount, springs, second axle, rims tires, brakes for the 2nd axle...it gets pricey even if you can do the work yourself. At that point you might be better off just buying a tandem, and selling the trailer you have. Now if like some manufacturers the frame for the single with a 3500 axle and the frame for the single with a 5200 axle is the same, then changing to the higher capacity axle (springs, brakes rims tires) is not quite as expensive, do-able, as long as the single handles well enough for you...

[Biged007]

Dave just adding my .02 I'm guessing what you have there is a Calkin Mirage anyway from your description it should be a full roller single with 15" wheels if this is true it's in fact a 3K min. could be 3500 at least that's what I was told at the marina while I was getting parts for my beast also as I remembered am was told the info on the faded tag should be repeated somewhere in the form of a stamping usually on one of the cross bars.

Okay now for me personally I also have a BL Capri but the smaller 1950 version and mine tips the scales at 1995 lb.s sitting on a Loadrite single with 15" wheels and 6 ply tires so I'm thinking pretty much apples to apples. what I can tell you is although It tows pretty well but it does kinda tell ya to keep your ^&%$^ wired tight and pay VERY close attn.

All in all I guess it depends on distance,speed and how much you will be pulling your baby around. In other words very little, prob. no worry's given very good or new tires, Quite a lot a tandem may be in short order as suggested above
Ed

[rwidman]

The frame of the trailer happens to ride ON the axle so no extra load is added to the frame. In fact it helps the frame since now the load is supported at an extra point.

Yes, but the GVWR stays the same so the weight of the axle, wheels, and tires must be deducted from the capacity. It also makes the trailer heavier and that might be an issue with the tow vehicle.

[rwidman]

Adding a second axle would be a way to go in my opinion. I know Rwidman won't agree(of course he never does) but how can adding a second axle to an existing one axle trailer make it any worse? Its still the same load! Its not like you are putting on a bigger boat on than what you have. You are just adding some safety margin.

You can add a second axle or even a third if you wish. Like a chain, a trailer is only as strong as the weakest link. If the frame is rated for 3500 lb, an additional axle or two will not increase the capacity. You would have to contact the manufacturer or hire an engineer to determine the capacity of the frame.

You cannot just add an axle, you must move the existing axle forward or back so each is equidistant from the original location. While you may feel that one set of brakes is sufficient, many states require brakes on all axles, even unecessary ones. Of course, you will need wheels and tires and you will need new fenders. You will have to readjust the tongue weight once you are finished. A multi axle trailer must be towed level so you may have to purchase a new ball mount for the tow vehicle.

There may be a safety factor in case of a blowout, but thousands of trailer haulers are using single axle trailers and there doesn't seem to be a rash of blowout related incidents. A multi axle trailer is harder to manuver in tight spaces, and of course, the tire and brake maintenance is double with two axles.

If the boat is properly supported and legal on a single axle trailer, I would suggest leaving it on one. If not, I would suggest purchasing a ready made trailer with the capacity for the boat.

[bruceb58]

Yes, but the GVWR stays the same so the weight of the axle, wheels, and tires must be deducted from the capacity.

So your logic is that the carrying capacity is now lowered by adding a second axle...interesting logic. So if I had a beam in my home that was supported by 2 posts and I added a third post between the other two posts, your logic would be that the supporting weight of the beam is now less than when I started? No different than adding another axle. I am not proposing that the OP put more load on than he has now.

True that the overall towed weight is now more by the weight of the axle and two tires and has to be taken into account. That is the one thing you have right.

[Biged007]

Sorry guys I'm just bored tonight but here's another ave to run down.
Now for myself here in Ct. if needed I would buy a tandem NOT make one Why?
one answer The D.M.V. or as I put it The dept. of mental vegetables.
Ten years ago I built a motorcycle trailer and had to have it insp. as a home built. Okay that's fair I take it down and it fails why? 15" rims putting it in the 3000# range and no brakes. explaining to the inspector that I was registering it for only 1500 made no difference and wouldn't discuss it. 1 hour later I return with a set of borrowed 13's and it flew thru My point this is the mentality you are dealing with.

[rwidman]

So your logic is that the carrying capacity is now lowered by adding a second axle...interesting logic. So if I had a beam in my home that was supported by 2 posts and I added a third post between the other two posts, your logic would be that the supporting weight of the beam is now less than when I started? No different than adding another axle. I am not proposing that the OP put more load on than he has now.

My logic is that since the maximum GVWR has not gone up and the trailer now weighs more, the capacity is less. It has nothing to do with beams in your house. There is no GVWR on a house.

[Frank Acampora]

But adding an axle does increase the GVWR! you are using the rating on the capacity plate in your logic. Adding the axle will increase the load the tow vehicle is carrying thus reduce its capacity for loads other than or in addition to the towed vehicle.

However, adding an axle just will not be economically feasable. You have the cost of the axle, tires, rims, and mounting hardware. Then you need to get the link between the springs----easier to just sell the trailer and buy a higher capacity one.

AND: If the hull is so far greater in weight than trailer capacity, you will also need to add bunks or rollers for extra cost while the frame still may not be able to adequately take the load.

So rwidman, I agree with you, but for different reasons.

[rwidman]

The "official" or legal GVWR will not go up.

[proaudioguy]

I don't see how adding a torsion axle would be as hard as you guys are describing. The debate of cost, legality, etc is another issue. Simply sliding one torsion axle and adding a second with another set of wheels and tires seems pretty simple to me. Maybe someone that has done the work can chime in on that.