I am biulding a hitch to tow my 23 ft jet boat behind my 24.5 ft 5th wheel.my boat and trailer weighs 7100lbs. I don't know the tongue weight but I can't lift it and it is very heavy. I thought of extending my boat trailer tongue a few feet but my neighbours thinks this will increase tongue weight? Thoughts please. I can't move the boat back farther on the trailer as this puts too much weight on the rear axle of the boat trailer.

Brian,I have a Yamaha 242 and the tongue weight is 500-600 pounds. A good approximation is 10-15% of your total weight of the boat and trailer. If a tandem axle and long tongue, boats tend to be a bit lighter on the tongue than say a travel trailer. That's still a lot of weight for the back of a 5th wheel trailer. You will need to seriously reinforce the rear structure of your trailer to accommodate a proper hitch setup.You will also need to be sure to have proper wiring for the boat trailer's electric brakes (hopefully it has them).The whole thing is problematic and generally not a good idea, but probably legal where you live. That is not the case everywhere, so research the law where you plan to travel, as you'd not want to get pulled over where it's forbidden.

just for the heck of it whats the max length for combination ?

I have towed tandem behind my 5er for going on 15 years now, so I do have some experience on this.In my experience, boat trailers are lighter on the tongue weight than a typical travel trailer. They seem to be closer to 7% - 10% of total weight. I have seen very few that are heavier, not saying that your's won't be.My worst experience was my first set up, with a boat that weighed close to the weight of the 5er, and too little tongue weight. I fixed that very quickly. My current set up is about 17,000 pounds over all. My boat is a 21' bow rider that weighs 5060 pounds. I would love to go up to a 24' boat, but I have no desire to tow more weight behind my 5er.Personally, I think you are likely to have a very unpleasant towing experience. A poorly balanced 2nd trailer, and a 5er that is very light just doesn't seem like a winning combination. It may seem counterintuitive but I think you would be much happier with a bigger, heavier 5er.For comparison, here is my set up. Photo taken this weekend.

Hi,I know a current truck driver that tows tandems at work. So he has the correct license and current medical certificate paid for by the company. The problem is his wife does not have a commercial license, his dad does, so will limit their travel days to what he can drive at one time. He is also a welder, and needed to attach a strong hitch to the trailer frame. By drilling a 7/8" hole into the frame tubing, then insert some 1/2" steel pipe, and then once he tightened the 1/2" bolt, he welded the tubing into place. This keeps the 1/2" bolt from crushing the frame tubing when tightened to 130 foot pounds. Fred.

Towing boat behind 5th wheel | Good Sam Community

dbbls
Explorer
Jul 01, 2014
A few years back I towed a boat behind my 5er. I kept breaking the springs on the 5er. I ended up adding a leaf to the springs and solved the problem. I guess it was close to the max and the extra weight on the rear put it over. I never weighed the rig but the boat and boat trailer weighed 3050 pounds.
Bionic_Man
Explorer
Jul 01, 2014
Bumpyroad wrote:
harold1946 wrote:
Bumpyroad wrote:
23 foot boat and 25 ft 5er and only 7100 lbs. I question that, with fuel, gear, etc.
bumpy

What part of "my boat and trailer weighs 7100 lbs." dont you understand.

I don't understand how your boat and trailer, both of which are longer then mine, can weigh that little fully loaded, fuel, water, gear, etc.
have you had them on a scale.
bumpy

The way I am reading it is he is stating that his boat and trailer weigh 7100 pounds (which seems high to me). That weight does not include is 5er. If he is saying that total weight is 7100 pounds, I would agree that seems light.
harold1946
Explorer
Jul 01, 2014
The OPs concern is tongue weigh, and the only way to be exact is with a scale.
Load it as it would normally be towed and take it to a scale.
Weigh the load on the tongue jack only. Done deal.
Brian_Shack
Explorer
Jul 01, 2014
I shopped long and hard to find a 245 trailer just to stay close to legal length in Alberta. With the f350 in front and the boat behind I am also worried that the 1st good frost heave might snap the trailer in half but it has an 8" channel frame full length. I'm not concerned about the hitch breaking more so the tow ability. Today am putting the axles under the springs, changing from 3 to 5 leaf pack and changing from 205/75/15 load range D to 225/75/15 load range E tires.
Brian_Shack
Explorer
Jul 01, 2014
I guess I should clarify the boat and boat trailer weigh 7100 lbs. the 5th wheel is 6040 lbs empty
JEBar
Explorer
Jul 01, 2014
having towed a golf cart on a trailer behind our 5er, I believe an additional point is worth consideration .... due to their widths, I can't see the golf cart trailer in my truck's mirrors .... I do have a rear view camera mounted on the back of our 5er and feel that offers some degree of safety .... in addition, I believe that it is very important to have a tire pressure monitoring system .... once while traveling at interstate speed, our Pressure Pro tire monitor sounded an alarm that indicated a problem with a tire on the golf cart trailer .... a glance at the screen for the rear view camera showed no problems .... I pulled over, walked around the front of the truck to go check the tire and a few steps later literally saw the tire blow out .... with out the tire monitor I wouldn't have known of a problem until the trailer was reacting to the blow out .... without the camera I probably wouldn't have known any thing was wrong until things got bad .... to me, the camera is nice, the tire monitor is essential

Jim
Bumpyroad
Explorer
Jul 01, 2014
Brian Shack wrote:
I guess I should clarify the boat and boat trailer weigh 7100 lbs. the 5th wheel is 6040 lbs empty

OK, the trailer is not the 5th wheel trailer.
bumpy
Mile_High
Explorer
Jul 01, 2014
Brian Shack wrote:
I guess I should clarify the boat and boat trailer weigh 7100 lbs. the 5th wheel is 6040 lbs empty
I guess only a boat owner understands the concept that the boat and trailer are two different vehicles - different registration, different specs, weights called out separately.

Extending the receiver definitely changes the dynamics on tongue weight. I looked at a motorcycle rack for the front of my truck, and although the carrier was rated for 500 lbs, the 2" receiver extension that was an option reduced that to 300 lbs per the manufacturer.
tegu69
Explorer
Jul 01, 2014
Brian Shack wrote:
I guess I should clarify the boat and boat trailer weigh 7100 lbs. the 5th wheel is 6040 lbs empty

So the caboose weighs more than the middle of the train, beautiful.
laknox
Nomad
Jul 01, 2014
tn terry t wrote:
just for the heck of it whats the max length for combination ?

Depends on state. Range, where legal, seems to be from 65-75'. Here in AZ, it's 75', last I knew.

Lyle