Trailer axle adjustment

[Bushwacker]

Originally Posted by Big fish

I'm about to install a 500 pound engine on a 20" bracket. I was just wondering how far should the single axle be moved back if any to compensate for the weight shift. Any ideas? The fuel tank has also been moved about 18" forward.

If it's a single axle trailer, I assume it's a 20' hull? If it has the 6000 lb axle with 6-lug wheels like my EZ-Loader, the trailer should have enough weight capacity (~4000 lbs), but I know from experience that a 500 lb motor is really too heavy for that hull, especially on a bracket, unless you've also moved the console forward a bunch. If you haven't installed it yet, I'd consider a lighter motor. Regardless of what motor you use, I hope that bracket has a big flotation tank on it to insure it'll self bail at the dock with the plugs out! If you want to be able to plane below about 20 kts, plan on running a good stern lifting 4B prop and a fin on the AV plate!

If you make many long distance tows, assume you'll want to do so without much gas in the tank to minimize towed weight, so moving the gas tank won't help your trailer balance. How far you move the axle depends on what sort of motor weight/position the trailer was set up for and if you've changed where the boat sits on the trailer. If it's a bunk type trailer and you have room to move the winch stand forward, you might be able to just move boat forward on trailer. Here's one data point that should get you in the ball park: I went from a 300 lb motor on the transom to a 427 lb motor on a 30" Hermco bracket, and I had to move the trailer axle aft about 12" to keep enough weight on the tongue for stable high speed towing. It's a roller trailer adjusted so the aft rollers were right under transom, so I didn't change position of boat on trailer. Wasn't hard to move the axle, as the springs on my trailer are attached to sections of galvanized steel angle iron which the trailer frame rests on, so all I had to do, with the boat off the trailer, was to just mark how far I wanted to move the axle, loosen the U-bolt nuts, chock the trailer wheels, hook up truck and pull forward till marks lined up. However I had to find a longer flexible brake line to connect the steel lines on the axle and trailer frame to keep the brakes operational!