Trailer: dual to tripple

[dscribner]

Any thoughts on this? Is it as simple as adding another 3500 lb axle to a tandem axle trailer to add another 3500 lbs of capacity or is the frame that much of a concern? My thought is that if I simply added the axle, and put a 30' boat on a trailer designed for a 25 footer, that would shift the bow 2 1/2 feet forward, the stern 2 1/2 feet back and keep the load balanced over the wheels. Provided the tongue was long enough, what am I missing? Am I being stupid for considering it?

 

[SwitchintoglideIII]

Are you actually adding 3500 lbs more boat weight? Legally 80% allowable would give you an extra 2800 lb capacity.
Is your trailer home built, or manufactured?
Is it steel or aluminum?
Anything is "doable"...

 

[31seahorse]

Provided the tongue was long enough, what am I missing? Am I being stupid for considering it?

I would also consider beam, support placement, axle placement, total weight, towing vehicle, ability to turn the trailer, reason for loading onto the trailer (move over the road or storage), how to put the boat onto the trailer (travel lift or float on ), ability to raise and lower the mast. OK, I have talked myself out of that adventure. We considered putting our Oday 272 onto a trailer for cheaper storage, but decided against it somewhere within answering the thoughts above.

 

[Tucson Sailor]

We owned a Catalina 25 with a dual axle, Trail Rite trailer for many years. Then we built a triple axle trailer for a Catalina 28 and now have a Catalina 30 on it which weighs at least 10,000 pounds. I towed it 1,200 miles last summer and it was solid, safe but still a load. I figure the trailer and boat were at leat 12,000 pounds. By the way, a 3/4 ton Ford diesel towed it just fine.

The difference is three 5,000 lb axles to carry the trailer frame itself plus the boat and stuff. The next difference is the frame. Our Trail Rite was box iron (open on one side). The other trailer has a full box frame easily 2" x 6" (maybe more, sorry, I don't know my steel). The size and weight goes up substantially from 25 to 30. Finally, the trailer must be much longer to fit the 30 foot boat because it needs more support pads. So, I'd think your plan would be safe going up a few feet from 25. Beyond that maybe you could sell the smaller trailer and invest in an oversized unit that allows you to pull the rig stress free? Good luck, be safe.

 

[Crazy Dave Condon]

dscribner;

A lot depends on the trailer you are asking about. As pointed out, there is a lot to consider. First is the frame capatible to carry that much weight. Second would you need two or three axles. Two axles depending upon size and carrying capacity will make a difference. Third, tire capacity. Supports i.e. bunkboards vs. stands with screw pads and you might want to consider four stands vs. three each side. This is not the forum to ask that question but one to ask a trailer mfg.

I am not an engineer but did design trailers for boats after being taught by a friend who actually designed them and knew what he was doing. My main trailer was a heavily built frame on two large tractor trailer style axles that used basically tractor trailer tires with many plys but the axles were torsion bar axles to carry the load absorbing bumps more readibly. Loading the boat onto the trailer has to be exact or you could bend the forward frame should a boat move accidentally forward which did happen transporting a Catalina 310 which occurred when my driver had to brake suddenly and the load shifted forward quite a bit due to an idiot driver that cut right in front of him on the interstate. My driver did not secure the load allowing the mfg. to do that and did not check on the tie downs during transport. I added support under the forward frame when repairing the trailer.

One thing if you should proceed, design the trailer should the load should shift accidentally 2-3 forsward if not properly secured. I always taught my customers to strap the boat down with straps addl. straps running from the front backward secured to the trailer and vice versa with the back should the bow of the boat not rest on the trailer winch stand. This is based on nearly 50 years of experience both personally and professionally.

 

[LloydB]

It would depend on the frame. The mass now should be balanced nearer the rear of the forward tire. If a third axle were added then both existing axles would need to be moved to allow balance over center wheel.

 

[woodster]

you also need to consider where to land the keel on the trailer ...the boat sits on the keel and the stands keep it balanced upright fore and aft and to and fro...also strap your load with the straps angling back from the front and angling forward from the rear along with crossing from port boat to starboard trailer and vise versa in the rear just like crossing your dock lines in a storm between the pilings