We had a customer stop by our shop and asked if we could come listen to a strange noise his
recently purchased boat was making. The boss went down to the boat (which was tied up at the
dock) and came back saying it had a knock to it. Today I got out the stethoscope and
verified it had a connecting rod knocking in it.


This boat started up and ran fine in the driveway, but the seller refused to go for a "sea trial". (see below)

The boating season is around the corner and some of you may be thinking about buying a used
boat. Here's KB's "used boat checklist" to help you make an informed purchase.

First off, perform these checks when initially looking at the boat.
1 –– Visual inspection of engine. How does it look? Oily,rusty,corroded,wiring rotted?
2 –– Compression check 100 psi minimum for 2 strokes, 4 strokes will vary but should be
150ish. All cylinders should be within 10%. (although Merc now says 15%)
3 –– Spark check using proper spark checker. (This test mostly for outboard ignitions)
4 –– Gear lube inspection. Remove the drain plug just enough to allow a bit to dribble
out. Water means there's water in it YIKES! Rusty water is a double YIKES! Milky oil is
contaminated with water (leaks) Black oil means it's overdue for a change. New oil will be
transparent, just tinted different colors for different brands. Small amounts of metal
shavings are to be expected, chunks are not.
5 –– Run on hose. Start it up and let it warm up for a few minutes. Make sure the
propeller isn't going to contact anything, and shift it in and out of forward and reverse.
Allow some time between shifting it between gears to allow the prop to stop rotating.
6 –– Inspect the transom for cracks or rotting. Especially near the bottom of the stern
bracket (outboards) or gimbal housing (sterndrives). Inspect the deck (floor) and the
stringers (big ribs/beams that run the length of the boat) for rot and or softness.
7 –– Batteries How old are they? Are the terminals corroded? Does it look
"pregnant"(swollen). Batteries are pricey these days and old batteries are a good tool for
lowering the price.
8 –– Service When was the boat serviced last? In most cases it will run about $500 per engine (sterndrive) and a little less for an outboard. If the boat hasn't been serviced for the season, you should deduct the service price from the selling price..another tool.
9 ––- Bellows and transom rubber (sterndrives) These are the rubber "boots" or bellows that connect the drive with the boat basically. These should be changed about every 4 or 5 years. Sooner if the boat is kept in the water. This repair runs between $500 and $1000 per engine/drive...another bargaining tool.

If all this checks out, then it's time for a "sea trial". One strong note of caution
here..If the seller won't take it for an on the water test...RUN AWAY! Don't let the seller
BS you and say "I don't give boat rides" or "I don't have time".. RUN AWAY! (see above)

One tactic is to go through the checks I describe above in the driveway. Negotiate a price
with the seller. Then tell him the sale is contingent on the sea trial. This forces the
sellers hand. If the seller agrees to the sea trial and the boat performs as it should on
the water, you probably have a sound boat.

During the sea trial, take note of RPM's at wide open throttle, oil pressure and temperature. Listen for any "rumbling" sounds from the transom., especially when the steering is hard over to the right or left. Note steering effort too. Stiff steering indicates a bad cable or helm, corroded/bound pivot or tilt tube (outboards) Sterndrives with power steering can be stiff from bad cable, pump or steering ram, rusted or corroded steering pin in the gimbal housing. Check shifting again. Does it go in and out of gear easily? Does it stall when shifted into gear? How does it idle in gear? Check for hesitation upon acceleration and stalling when coming down off of plane. Finally, check the bilge for water.

Need I say more?

If you aren't mechanically savvy, take the boat to a shop and have it checked out. The shop
you choose should be on the water or have a dyno to do the sea trial. The dyno will only
confirm engine/drive performance. It won't tell you if the boat leaks! Expect to pay the
shop for an hours worth of labor per engine. A wise investment for such an expensive toy.

I surley can't say you won't have a problem with the boat after performing these checks, but
they will eliminate 99.9% of all the problems we see with newly purchased used boats.
Shoot me an IM if you need info on specific models and or problems. Happy boating!
KB

Thanks KB.

good info Thanks!

SUBscribed, as my dad is looking to buy a used boat in a few months.

Let me know if you have any questions about a specific make or model.

Thanks and will do.

The only information he's given me is this:
Saltwater
Fun
Capable of fishing
Cheap
No sails

Beyond that, I guess I'll more information as the Spring and Summer go on.

KB, I am going to look at a 1989 Ranger 363 with a Mariner 150 on it. The oil injection has been removed and the owner has been adding oil to the main tank. I am going to take a compression gauge with me, anything else i need to look for on this particular engine?

Edit: What about todays ethanol fuel in the older engines? What octane would you recommend?

Thanks for any info

Compression, check for water or milky oil in the lower unit, spark with proper tester, wiring condition as mentioned in the original post. Mixing your own oil is fine. Many of the oil injected motors have had the oil pump removed. They sometimes shred the plastic drive gear on the crank for the oil pump. This is why some are removed. Alcohol in the fuel will make the rubber hose and other rubber components in the fuel system brittle. Mid grade or premium fuel will help prevent detonation.
Take note of the RPM's at wide open throttle. It should be within the motors recommended RPM range...4600-4800 IIRC for that motor. It will say what the RPM range is on the transom bracket.
Take it to the lake and run it on the water!! Running on the hose is only a preliminary check.
Find out when it was serviced last. If it needs service for this year, you can use that as a bargaining chip.

KB7DX has always let me bother him and gave me an opinion! It's what makes arfcom great! His service here is greatly needed and appreciated, and he knows his stuff! Sorry KB for aggravating you so much. Moneys hard to come by lately and i'm gonna use EVERY resource available before i spend mine. Thanks again KB

Thanks smalljaw. One of the worst aspects of my job is informing the customer that his newly purchased boat needs thousands in repairs. This discourages new boaters and alot of the time they just sell the boat at a big loss and forget about boating forever.

On a lighter note, another bad aspect of my job involves pulling all kinds of...ummm....stuff..out of Vacu-Flush toilets.

Anyways, if anyone needs advice on a boat or engine, IM me. I have been working on boats professionally for 8 years. I was an auto mechanic before I attended MMI in Orlando. If there is something I don't know, I can ask the older techs at work who have been in the industry for 30 plus years.
KB

Story time!!!

OK, we had a marina member who was quite the ladies man. He would have several bikini clad chicks on his boat every weekend. Every Monday morning, we would get a call from him saying his "head"(toilet) was broken again and wanted us to fix it under warranty as we had fixed it several times before. This time, we fished the used "feminine hygene product" out of the system and saved it in a baggie for him. When he showed up the next Saturday, we presented him with the prize. We told him we didn't warranty things like this. He said.."oh well, you pay for it one way or the other.."

lulz...glad i don't have that job!

So the boat my parents are looking at now, is a 1989 Pro Line 17 foot center console with a 150hp Johnson motor. The motor has 30 hours on it and still runs. The owner still takes it out fishing.

ETA: Forgot to add, The owner is a friend of my parents, and is going to take my parents and I for a ride whenever we want.

Not buying a boat anytime soon but great info.

Tag.

How can someone check for a spun hub without putting the boat on water?

This bit me on the ass when I bought my boat. Didn't find out until I got the boat in the water and no ammount of throttle got me past the ducks swimming at the ramp.

There are a couple of ways to check for a spun hub out of the water. The first way, and safest I might add, is to remove the prop and look for rubber chunks where the splined hub is molded into the prop. This obviously only works for a molded rubber hub. The newer Mercury/Quicksilver props have a replacable plastic hub. In this case, you remove the splined hub from the plastic insert and look at the insert's condition. It may take some tapping with a mallot to remove the plastic insert, but most of the time it's real obvious when it's spun.
The second way is to place the engine in forward gear and try to rotate the prop backwards by standing on one of the blades. This is the most dangerous way!! Make sure the engine cannot start! Do not do this on a warm engine! Remove plug wires (outboard) or coil wire (inboard/sterndrive) .
This method is not 100% accurate. Sometimes a hub will pass this test, but slip when loaded in the water.

Bump. It's spring again! Any perspective boat buyers have any questions?

this ^

Good info. Thanks!

KB, I'm only getting 43MPH at 5300RPM out of my OMC 99' FITCH 115HP on my old heavy (1450 Lbs. dry hull) 83 17' Pro-Line CC. This has been the case since I rigged the engine back in 03'. It has a 17" pitch SS Michigan wheel. Manual says I should get 5500-6000RPM for a good wheel match. A Very reputable local prop shop says they can jig and beat out some pitch to get another 200-300RPM for $125. Boat has a great hole shot now and good cruise at 25MPH at only 3500RPM. I think going to a 15" wheel will send me over 6000RPM WOT. What should I do? Leave it alone or settle for the 200-300RPM gain with the re pitch? Another 5MPH top speed at 5800RPM is my objective and would be perfect.

Generally speaking, decreasing pitch "one step" (17 down to 15 pitch) will gain you 200-300 RPM's. Best thing to do would be to try some different props/pitch. See if the prop shop will lend you a few different props to try out. You will most likely have to leave a $$ deposit (unless you know them well) on the props. Take them out and try them. Propping a boat correctly usually takes going through several prop styles and pitches. You will find that some props perform better than others even with the same pitch. Michigan Wheels aren't known for their "performance" capabilities. Some guys find they need two props. One for a heavily loaded boat and one for a lightly loaded boat. How is the hull on your boat? Does it have any irregularities, hooks, rockers or rough bottom due to marine growth?

Hull is clean. Simple modified Vee. My old OMC 115(carbs) would 45MPH at 5700RPM with same prop. I was told the 115 fitch runs the V-6 gear case with a different gear ratio than the 3 cyl and old V-4. If this is true I might just try a 15".

I don't know if the ratio is the same, but there are a few different ratios out there. Wouldn't hurt to try a 15 pitch.

Good info!

I just sold my 4-wheeler yesterday, so I can buy a boat.

I've been looking at a LOT of different boats lately, now that I have cash in hand, I can get serious about looking.

One that caught my eye was an 1987 "Wahoo Bay Boat", with a 1988 yamaha 70hp.

I'm wanting to go take a look at it this weekend.

Any "known" issues with this boat/ motor ?