Converting Single Axle to Tandem Axle Trailer? - The Hull Truth

TRAVELLER · 06-23-2008, 01:50 PM

I have a 2008 Boston Whaler 170 Montauk. I traded in the trailer that came with it for a really nice Loadmaster single axle trailer. I just got home from my second trip from NC to FL, and had a tire slowly losing air. Since there is only one wheel on each side, I spent most of the trip watching the tires and realized somthing was wrong before things got bad. I changed out that tire for the spare and made it home with no further incident. I later found a nail stuck in the tire that had been going flat.

Considering that I trailer a boat 8,000 - 10,000 miles a year, I've realized that I would be happier and safer with a tandem axle trailer. I don't even like to think about what it would be like on the interstate if I had a sudden flat tire with a single axle trailer.

I'm thinking about adding a second axle to make this trailer a tandem axle trailer. There is plenty of room for the second axle on the back of the trailer if the current single axle was moved forward or back. Assuming that the present axle is in the proper location to balance the load, if the two axles were equidistant from the center of that spot, the balance should stay the same. Does this sound like a doable project?

UaVaj · 06-23-2008, 02:03 PM

Unless it is hard mounted. Yes it can be done. You can even move the axle up or down the length of the trailer so you can adjust the tongue weight if needed.

If I was trailering that kinda of milage. I would make sure that one axle/tires alone would be strong enough to support the whole rig. The second axle would be a full backup.

ngirolamo · 06-23-2008, 02:04 PM

If you trailer that often ,an that frequently, get another trailer outfitted the way you want , and b done with it..

rwidman · 06-23-2008, 02:50 PM

Quote:

ngirolamo - 6/23/2008 4:04 PM

If you trailer that often ,an that frequently, get another trailer outfitted the way you want , and b done with it..

If you have to ask, then I agree with ngirolamo.

You'll have to figure out where to put the axles, how to mount them, how to align them, and you will have to add brakes and redo the brake tubing. And you'll have to buy the materials. A factory tandem axle trailer will have all this done and done correctly. Add your boat and hit the road.

If one is mechanically inclined and has the tools and space to do this and would just as soon be messing with a trailer as out boating, it's a doable project.

TRAVELLER · 06-23-2008, 05:18 PM

Thanks for the responses so far.

The Montauk weighs 1400 lbs. The outboard weighs 410. Gas and batteries probably add 200 more lbs., for a total of 2010. My trailer is stamped with a rating of 2990 lbs, and has no brakes on it. If it had been rated at 3000 lbs - just 10 lbs more, I would have been required to have brakes in Florida. I pull the boat with a Dodge 2500 w/Turbo Diesel, and stopping this package is no trouble at all, even on wet roads in a rain storm.

Every tandem axle trailer I looked at was rated for a minimum of 3500 lbs and came with brakes on at least one axle, sometimes both. Florida law requires brakes on all axles of a trailer rated over 3000 lbs. I want to keep the 2990 lb. rating of my present trailer so that brakes are not required, and add an axle to this trailer if it's possible.

jeffnick · 06-23-2008, 06:28 PM

Take it to Wesco in Columbia SC and have them make it a tandem.
What I did

crparmelee · 06-24-2008, 05:59 AM

I look at a tandem trailer like I do at twin engines - double trouble. Twice the tires, axles, and bearings to maintain or fail. I have trailered boats about 80,000 miles in the last 30 years on single axle trailers with no major problems. I do watch the tires closely though, and replace them at the first signs of failure. A set of tires is usually good for 5 to 7 years. They don't wear out, they die of old age.

Does a Montauk 17 hull weigh 1400 lbs? These used to be light hulls, less than 1000 lbs.

TRAVELLER · 06-24-2008, 06:34 AM

crparmelee - You're right about the weight of the old design of Montauk. The old model weighed about 900 - 950 lbs. The Montauk 170 was introduced as a new model in 2002 to replace the classic Montauk. It's a longer, wider boat, with a deeper V than the classic Montauk. That's where the additional weight came from.

rwidman · 06-24-2008, 06:57 AM

Quote:

TRAVELLER - 6/23/2008 7:18 PM

Thanks for the responses so far.

The Montauk weighs 1400 lbs. The outboard weighs 410. Gas and batteries probably add 200 more lbs., for a total of 2010. My trailer is stamped with a rating of 2990 lbs, and has no brakes on it. If it had been rated at 3000 lbs - just 10 lbs more, I would have been required to have brakes in Florida. I pull the boat with a Dodge 2500 w/Turbo Diesel, and stopping this package is no trouble at all, even on wet roads in a rain storm.

Every tandem axle trailer I looked at was rated for a minimum of 3500 lbs and came with brakes on at least one axle, sometimes both. Florida law requires brakes on all axles of a trailer rated over 3000 lbs. I want to keep the 2990 lb. rating of my present trailer so that brakes are not required, and add an axle to this trailer if it's possible.

It's generally not a good idea to have a trailer rated far in excess of the weight of the boat. The suspension doesn't work right and the boat will take a beating.

You have a pretty light load for the trailer you alsready have, I don't think it's a good idea to add another axle.

If you use good tires and inspect and maintain them you should be fine with a single axle trailer. Many people trailer their boats with a single axle trailer with no problems.

pappastratos · 06-24-2008, 07:09 AM

Quote:

crparmelee - 6/24/2008 6:59 AM

I look at a tandem trailer like I do at twin engines - double trouble. Twice the tires, axles, and bearings to maintain or fail. I have trailered boats about 80,000 miles in the last 30 years on single axle trailers with no major problems. I do watch the tires closely though, and replace them at the first signs of failure. A set of tires is usually good for 5 to 7 years. They don't wear out, they die of old age.

Does a Montauk 17 hull weigh 1400 lbs? These used to be light hulls, less than 1000

lbs.

I agree

Rascalsdad · 06-24-2008, 10:27 AM

I went through the same process you are considering just so I'd have four tires on the road. I had it done at a local trailer mfg. for $550 including tires and rims. They didn't have to move the original axle though so that kept the cost down.

The additional maintenance of two axles vs one is hardly worth any concern especially given the huge advantage in safety. If you do get a flat it's not a big deal, still got 3 tires on the road. I say go for it, especially for the long tows you mention.

The trailer is easier to handle now, you don't have to oversteer going around corners and it responds more quickly when maneuvering at the ramp.

bamaboy473 · 06-24-2008, 10:30 AM

Quote:

TRAVELLER - 6/23/2008 6:18 PM

Thanks for the responses so far.

The Montauk weighs 1400 lbs. The outboard weighs 410. Gas and batteries probably add 200 more lbs., for a total of 2010. My trailer is stamped with a rating of 2990 lbs, and has no brakes on it. If it had been rated at 3000 lbs - just 10 lbs more, I would have been required to have brakes in Florida. I pull the boat with a Dodge 2500 w/Turbo Diesel, and stopping this package is no trouble at all, even on wet roads in a rain storm.

Every tandem axle trailer I looked at was rated for a minimum of 3500 lbs and came with brakes on at least one axle, sometimes both. Florida law requires brakes on all axles of a trailer rated over 3000 lbs. I want to keep the 2990 lb. rating of my present trailer so that brakes are not required, and add an axle to this trailer if it's possible.

Adding an extra set of wheels and an axle will push the weight over the 3000# limit. Is it possible that you'll get your boat/trailer weighed by some agency; after which you'll be retrofitting brakes?

Myott · 06-24-2008, 01:19 PM

DId you think about a spare tire and hub?

GhostShip · 06-24-2008, 01:56 PM

I think rwidman's right on the money.[img]../images/emoticons/thumbsup.gif[/img]

Your going to beat-up your boaton a dual axle rig at that weight. Spend the money on a couple of frame mounted spares, spindle and hubs w/ prepacked bearings(if your spindles are replaceable), a tire repair kit(plugs work fine for a looong time), air compressor and the tools to do the work "in the field". I've towed alot w/ single axle trailers and the only problem I've ever had was actually wearing out 2 sets of tires on a trip from Wisconsin to Fla and back. Turned out to be the axle was way out of alignment on my freinds trailer(w/ the baby wheels). It may be that we wereALWAYS prepaired, but it's never been a big deal.

With the afore mentioned "stuff" and a walk-around at every gas stop you should be fine! Speaking of gas, that extra axle will hurt you gas mileage too.