To the new subscribers, may I introduce myself to you. I am Jack McCarthy, owner of The Wooden Boat Shop in Cincinnati, Ohio. We are a full-time business involved in restorations, repairs and general service of antique and classic wood and fiberglass boats. We specialize in structural work of every kind and are deeply involved in rebuilding and repair of all straight inboard engines and transmissions. We are a fairly large shop with seven full-time boatwrights, not including myself.

This month, I have been asked by the editor to write on the propulsion systems of a straight inboard boar. We are going to cover shaft log/stuffing box maintenance, strut bearing replacement, engine alignment, propeller maintenance and repair and transmission service. I will list procedures to follow for each job title, which will enable you to do a step-by-step repair.

1. Strut bearing maintenance:
First let's start off by explaining what the strut bearing actually is. The strut bearing, in most cases, is a very hard rubber sleeve vulcanized to a brass sleeve that is pressed into the strut that holds the shaft just ahead of the propeller. The water it runs in lubricates this bearing. One way to check to see if it is bad, is to grab the propeller and shake it. If you feel any movement, it's time to replace it. The only positive way is to remove the shaft from the transmission, slide it out past the bottom of the boat and then see if there is any movement. This way, you have accurate measurement. Now below, I will list procedures to replace the strut bearing.

NOTE: We have all sizes of strut bearings in stock.

a. Remove propeller from the shaft. Please ---DO NOT beat it off with a hammer, use a prop puller. You may want to use penetrating oil a couple of days before your do this.

b. Remove the setscrews from the side of the prop shaft coupler flange that bolts to the transmission. Some Centurys used a roll pin that you would drive out with a punch; also, loosen the packing gland nut.

c. Using a slide hammer and a coupler nut, put the coupler on the shaft and then on the slide hammer. Then, slide hammer it out of the coupler and out through the stuffing box and finally through the strut.

d. Next, remove the bearing out of the strut by taking a hack saw, removing the blade from one end and passing it through the strut and reconnecting it to the saw (use a new blade), then saw through the strut bearing and its brass sleeve. Now, please be careful not to saw into the strut itself - so stop and check many times.

e. Use a screw driver and a hammer and drive the screw drive along side your cut and the sleeve will peel up, reducing the diameter, then just simply punch it out.

NOTE: On some Centurys, there are set screws in struts to hold the strut bearing. Remove these and it may come out without cutting it.

f. Now, clean out the inside of the strut making sure it's all clean and free of any burrs or corrosion.

g. Purchase the proper strut bearing. Measure the inside diameter of the strut, the length of the old strut bearing and also the length of the strut to make sure and the diameter of the prop shaft. Then you cane order the proper bearing.

h. For the amateur mechanic, go out and purchase a piece of 3/4" all thread, two nuts and four washers. Take your strut and swab some STP or other anti-friction compound on the inside diameter of the strut and the outside of the strut bearing. Run a nut and two washers on the one end of the all thread, take the strut bearing and check to see if either end fits farther into the strut, run two washers followed by the nut on the strut bearing side until snug. Now, very carefully, make sure you have the strut bearing perfectly perpendicular to the strut. Start tightening the nut on the strut bearing side. Watch carefully that the strut bearing is going in straight. Once it is in about one inch, just keep tightening until it's flush with the strut. IF you so desire and have a press, remove the strut and use a press to press in the bearing, again making sure it's perpendicular to the strut and use a plate or machined piece to use with the press.

i. Now you're ready to go -
NOTE: This would be the best possible Time to repack your shaft stuffing box on your shaft log or maybe convert to a dripless packing that they sell now The new dripless packing starts at $266.00 for the best kind. Now, if you want to repack your old stuffing box,the cost is about $7.20 for the packing and about $4.00 for a new hose that goes from the packing gland to the shaft log. I will list below the procedures to install new packing.

a. While the shaft is out, loosen the clamps on the packing gland (stuffing box) and the shaft log.

b. Remove the unit from the boat, measure the hose inside diameter and the length. Take a trip to your local NAPA store or good part's store and ask for a reinforced wall hose in the same inside diameter and length or call us and we will send you one. Also, purchase some new stainless steel clamps the proper size to fit the outside diameter.

c. Remove the outer cap from the shaft log, remove the old packing, clean up the entire assembly, cap, jam nut and base.

d. Measure the outside diameter of the shaft and the inside diameter of the cap piece. A typical dimension is 1" shaft 1 1/2" cone or cap, divide the difference in the dimensions by 2 and you'll have 1/4". Packing comes in 1/8", 3/16", 1/4", and 3/8", and so on.

NOTE: We stock all sizes of the paraffin impregnated flex packing.

e. Using a razor blade, cut three identical pieces perfectly, so that the joint butts firmly against the other while being tightly against the shaft.

f. Install these round pieces inside the stuffing box cone with each joint 180 degrees apart.

g. Install the jam nut (a thin nut) on to the threaded portion of the stuffing box followed by the cone just loosely on the stuffing box.

h. Using STP or your anti-friction compound, put it on the end of the shaft to make sure it will slide on easily.

i. Lubricate the shaft again in the entire area of the front and in the area of the strut, then run the shaft up through the strut, through the stuffing box then stop.

j. Position the coupler with the keyway facing down, install the key. Now using two people, push the shaft up to the coupler while the other person is guiding it in the coupler and lining up the key to match the keyway.

k. Using the end grain of a 2" by 4" piece and a hammer, drive the shaft in , after you have it aligned, until you can see the "D" dents that are drilled into the shaft line up with the set screw holes in the coupler.

NOTE: Have the set screws out of the coupler, so you can see the "D" dents.

l. Install and tighten setscrews, then safety-wire the setscrews.

NOTE: Use stainless steel safety wires.

m. Install key and propeller, tighten castle nut and install a stainless steel cotter key. NOTE: If you have an aluminum boat, you must use a fiber non- metallic strut bearing. If anyone has questions about strut bearing replacement or shaft packing, just give me a telephone call at The Wooden Boat Shop(513/941-7281), or e-mail me at woodenbts@aol.com.

SHAFT ALIGNMENT

This is a tough one, because there are so many types of motor mounts, depending on the make of the engine or goat. Some use wedges, some have jackscrews.

a. To check alignment, disconnect the prop shaft coupler from the transmission output flange, usually four bolts.

b. Separate the coupler from the flange and with a feeler gauge, check the distance at three places 120 degrees apart on the flange. This is important and all three places should be perfectly equal.

c. If the top of the flange is tight and the bottom is loose, the front of the engine must come down. The same goes from side to side. It's pretty much a common sense thing.

d. Another quick check would be whether the shaft turns very easily in neutral with no play in the strut bearing.

NOTE: The only time for a totally accurate alignment is when the boat is in the water. You can get it close on shore, but for the final adjustment, the boat must be in the water.

If you should have any questions about any of these topics, give me a call or e-mail me and I will help you with it.

NOTE: In some cases, you just can't align the motor. If that is the case, have the shaft checked for straightness. If it is straight after being lathe checked with a dial indicator, then look to see if the strut is bent. In some cases this can be remedied without strut replacement.