Boating Tips

Bounce Beaters Save Your Transom

Posted 10/28/2011

It’s an all too familiar sight – the happy angler cruising down the highway with a boat in tow, and the big outboard on the back is jumping for joy every time the trailer tires cross a crack in the pavement. Our angler is thinking about fishing, while the outboard is considering jumping ship on the way to the lake.

The Flex Factor
A typical boat transom is around two inches thick, and an integral part of the hull structure, designed to transfer the engine’s thrust (pushing power) from the transom to the rest of the hull, enabling the boat to move forward.

An average 200-350 horsepower outboard tips the scales somewhere between 500-800 pounds, and only four bolts hold this monster to your boat. That’s fine for using the boat in the water; however, when you trim up the engine to trailer the boat, the outboard’s weight acts as a lever, trying to flex the transom. Given sufficient time, the transom will eventually fail – not a good thing for the boat, outboard, or your wallet.

Imagine taking a thin piece of plastic, say a credit card, and you bend it repeatedly. Flex it enough times, the card will crack and then break – just like a boat transom with a bouncing outboard bolted to it.
This phenomenon isn’t unique to high-horsepower outboards or specific hull materials; all unsupported outboards – no matter what the horsepower rating – will work against the boat’s transom without some kind of support to hold the engine in place.

The Fix
Ideally, we could trailer a boat with the outboard trimmed down, but this is impossible because the skeg would drag on the pavement and break off.

The solution is to trim up the outboard and secure it in place with a device generically called a “transom support”. A transom support reduces the outboard’s lever/bouncing effect to the point where it’s negligible.
There are several brands of transom supports on the market. Most consist of an adjustable bar that attaches to the trailer on one end and to the outboard’s gearcase on the other end.

Another approach is a composite tube, such as the Yamaha Outboard Trailering Support, that clips over the outboard’s trim rod (or ram) with the engine trimmed up. Insert the tube over the trim rod, and then trim the unit down until the weight of the outboard is on the tube.

Either product works well to keep the outboard in place during transit, as long as you use the transom support properly.

The key is getting into the habit of using a transom support. Make installing the support part of your pre-trip routine. Your transom will thank you for it. Y

Photo Credits:
Ranger® Boats
Yamaha Marine Group