Used Boat Deals: Moderate Fixes, Big Savings

One way to get a deal on a used boat stems from someone else’s misfortune: divorce, death, job loss, and so on.  All of those those things can lead to someone needing to sell a boat quickly. As I’ve said elsewhere,  as long as you’re not the cause of the misfortune, you might get a good deal on the boat and help out the seller at the same time.

Replacing a drive coupler is an expensive repair -- the part alone is upwards of $500. But the repair can be used as a bargaining chip worth much more. MerCruiser Marine Photo.
Replacing a drive coupler is an expensive repair — the part alone is upwards of $500. But the repair can be used as a bargaining chip worth much more. MerCruiser Marine Photo.

Another source of a great deal is someone else’s ignorance. We’ve all heard the urban legend about the widow who sells her late husband’s 1953 “Chevrolet” for a few thousand dollars. As the legend goes, the buyer shows up to discover it’s a Corvette, which he snaps up and flips for huge profit.

In the marine market, there’s no shortage of ignorance, which you can use to your advantage. Say you find a sterndrive boat that’s been sitting because the owner put it in the water one day and it exhibited a vibration, or went into gear but wouldn’t move. He’s baffled, and he’s so terrified of what it might cost, he wants out.

That’s where you come in. Odds are good the engine has fallen out of alignment with the drive, which is normal and happens over time. All boats should have their drives pulled and alignment checked annually to make sure that something is not moving. It’s also a good time to check and lube the universal joints, inspect the bellows, inspect the gimbal bearing, check the splines, and lube the drive coupler. If a previous owner never did that maintenance, that could lead to misalignment.

The alignment tool goes through the gimbal bearing to the drive coupler to test alignment. photo.
The alignment tool goes through the gimbal bearing to the drive coupler to test alignment. photo

In the case of vibration, the engine alignment probably just needs to be adjusted, which is simple enough if you have the factory drive alignment tool, which is little more than a metal dowel that acts as a go/no-go gauge. Any good shop has this tool, and the labor rate should be around $300. When the engine is properly aligned, you should be able to slide the alignment tool fully into the coupler easily and remove it with two fingers.

This video, courtesy of BoostPower Marine, shows the alignment tool and how it’s used.

In an instance where the boat goes into gear but the boat doesn’t move, a likely cause is the drive coupler, which is basically what connects the engine power with the input shaft to the drive itself. Bolted to the flywheel, the coupler is made of steel and compressed rubber, which can tear loose from the steel. That’s why the drive will go into gear, but the boat won’t move. The engine isn’t spinning the input shaft. Another sign it needs replacement is when you rotate the engine by hand and the alignment tool goes in easily with the engine in one position, but not in another. That indicates the drive coupler is not running true and probably needs replacement.

Replacing the coupler is a more expensive repair because the engine has to come out. But there’s a huge bargaining chip on the price of the prospective boat. If you know what’s wrong and the other guy doesn’t, you can use that do your advantage.

It’s not as good a story as bringing home a 1953 Corvette for a few grand, but then again, you weren’t shopping for a ‘vette, were you?


Boat Trader has plenty of  Buying and Selling advice, but also check out the hundreds of articles in the Boating section, with tips on everything from seamanship to maintenance, how-to, where to find replacement parts, and much more.


Inboard Engine Alignment

engine alignment
Aligning the engine with the shaft is key to eliminating vibration.

If you have an inboard engine on your boat and have excessive vibration, it may be due to the engine not being properly aligned with the shaft. Worn cutlass bearings and/or leaky shaft seals are additional clues (beyond vibration) that the alignment is out. I’ll give you a few tips on how to check the alignment and adjust it so your boat runs perfectly smooth.

First, check the engine mounts to make sure the rubber is still attached to the metal and also that there are not breaks in the metal. Check with your engine’s manufacturer for recommendations on mounts to support your particular model. Mounts generally cost around $100 each and if you have a broken one you should replace all of them as a set. Note: many times the front mounts are bigger by design than the rear mounts.

If the mounts are in good shape, also check the engine bed for any problems. Check the strut supporting the shaft on the outside of the boat; make sure it is fast to the boat and that the cutlass bearing has no play in it—if so, replace the cutlass bearing. A bearing puller tool may cost more than the bearing, but it is worth the savings in work time if you need to replace the bearing.engine coupling

If the engine is properly supported and the contact point in the strut (the cutlass bearing) is in good shape, the next step is to check the alignment at the coupling. The coupling attaches the shaft to the end of the transmission. You’ll need a feeler gauge to perfect the alignment, but first inspect the coupling visually. There are typically four or more bolts attaching the two plates. Ideally, these should be tight and the coupling surfaces parallel. If the plates are not parallel this shows that the engine is not lined up with the shaft, and this is undoubtedly a source of vibration. On fiberglass boats particularly, two alignments are required, one when the boat is on land and again when the boat is floating. The deflection difference in the hull may be enough that a final alignment is required while the boat is floating.

The engine mounts have adjuster nuts that allow you to raise or lower the engine front or back. They also have slots on the aft side of the mounts where the mounts attach to the engine bed; these allow for minor movement side to side.  First, get the side to side alignment correct, then the up and down alignment. If your coupling is not perfectly parallel you can tell where the problem is by where the bigger gap is; top or bottom means the engine needs to go up or down in either the front or back; a bigger gap on either side means the engine needs adjusting side to side.

cutlass bearing
The brass tube with rubber sleeve is the cutlass bearing. If it is worn by a misaligned engine, it can be removed by backing off the set screw and either using a press or by cutting with a hacksaw blade.

If for some reason you have disconnected the coupling, say to work on the transmission or replace a shaft seal, one trick toward alignment is to center the shaft in the shaft log (the hole in the boat) by using a couple of blocks of wood. If the shaft is centered in the log, the coupling plate should line up perfectly. Otherwise go back to the step above to align the engine with the shaft. If the shaft is not centered in the shaft log you can expect to have leaks.

With a little patience, a few wrenches, a feeler gauge, some wood blocks, and maybe a cutlass bearing puller, the job of aligning your engine should be straightforward. Don’t forget to check the alignment again while the boat is in the water. Smooth boating!