Slide The Prop On The Taper

Step 1 – The first step is to slide the prop, or prop hub, onto the shaft without the key. Be sure the shaft & prop hub are clean. Once it’s been slid into place, and seated as deeply as it will go, mark around the leading edge with a Sharpie marker, as seen in this photo.

Slide The Prop/Hub Onto The Shaft Again

Step 3 – Slide the prop or hub back onto the shaft again and seat it like you did when making the mark. Once seated, lock the shaft and spin the hub around it about five-ten times and remove the hub or prop.

There are a number of techniques to using Prussian Blue, I find this one works well but some prefer other methods. The only critical thing is that your method results in a good fit.

In this photo you can see a clean area at the leading edge of the taper where the Prussian Blue has been wiped off. This clean area is the only area this new prop and shaft made good contact. This represents less than 15% contact and even with the prop nuts tight you might have only ever see approx 20% contact. This can lead to point-loading of the shaft and a possible shaft fracture. With improperly fit propellers shafting fractures are not as uncommon as one may think they are. If the shaft fails you not only loose the shaft but may also loose a multi-thousand dollar propeller too.

This shaft was brand new and made by a shop that does military shafting and has the calibrated dies to test the taper. Not all shops have or use these calibrated test dies and they are normally only used to make sure the machines are in tolerance. This taper was tested, with Blue, and was spot on. That leaves the Flex-O-Fold prop taper as the likely culprit here.

This type of poor fit is not uncommon. The sad part is that many boat yards never even bother to check the fit and instead just slap the prop on. Fits like this are common because machines wear and differ slightly. The prop was machined at one shop, in another country, and the shaft at another.

Valve Grinding Compound

The compound you use for this task is commonly referred to as valve grinding compound. I’ve used Clover Compound by Loctite and also the compound by Permatex which is available at most any NAPA Auto.

For this task I do prefer the oil lubricated valve grinding compounds as opposed to the water based versions. With the water based product the prop seems to bind more and is grabby when rotating it around the shaft.

For this pictorial I used oil based Permatex brand but any fine valve grinding compound will work.

After Lap Fitting

Here is what it looks like after rotating and before wiping the valve grinding compound off the shaft. The picture with the compound wiped off came out all blurry so I’ll need to take another one at some point.

NOTE: The prop is the part that will give up more material as it is significantly softer than most shafting unless you have an old bronze shaft.

The shaft and inside of the prop should look evenly ground with no spots that have not been honed.

High & Low Spots

In this photo you will notice a couple of either high or low spots about half way down the inside of the prop & the concentric rings I was talking about.

This prop was worse before I started but the shots down through the bore never came out good enough to publish (note to self; remember to bring flash).

This photo was taken after about five rotations. I spun it a total of 22 rotations and these high & low spots were no longer visible making for a much better fit interface.

Install The Propeller

Step 8 – To install the propeller you’ll want to follow these simple steps:

1- Slide the prop onto the shaft, without the key, until it will not move any further.

2- Mark the leading edge of the prop where it meets the shaft with a fine tip Sharpie marker. This is your insert-depth mark. When installed with the key, and torqued down, you should no longer see the fine point Sharpie marking.

3- Install the key and slide the prop over it and up the shaft. If you can’t get to your mark the key is key-bound and the prop & key needs to be readjusted.

4- Thread on the big nut and insert a block of wood between the hull and prop to lock it.

5- Torque the large nut preferably using the correct sized wrench. These nuts are soft and can be rounded easily so a proper fitting wrench is a very good idea. The nuts for a 1″ shaft are usually, but not always, 1 1/4″.

6- Once the prop has been torqued down remove the large nut and replace it with the thinner nut and torque it down.

7- To properly torque the prop nut you may need a block of wood between the hull & prop. Please use extreme caution doing this with a folding or feathering prop, in fact, try NOT to. Even older fixed blade props that have been re-pitched can be too soft for this approach. Always use the wood as close to the hub root as you can get.

The best method for torquing the nut is to use a high quality strap wrench on the shaft instead of a block of wood but you’ll want a decent one as the cheap ones tend to slip on small diameter shafts.

The Cutlass Bearing

Replacing a cutlass bearing is not a tough project but does require some thought. On some boats the bearing is inside the dead wood making replacement more of a task than when it’s mounted in a strut. These instructions deal with replacing a strut mounted cutlass bearing.

TIP: To remove and replace a cutlass bearing with the shaft still in place I strongly advise using a Strut-Pro Tool.

While there are some commercial tools designed for cutlass bearing removal, such as the Strut-Pro they can be a bit pricey for a DIY to replace just one bearing. Some owners associations have purchased them and allow their members free use of the tool. The Catalina 34 organization owns one such tool. These tools work well and don’t require the shaft be removed, a big plus and huge time and cost saver.

Occasionally when a bearing has been installed for a while they can become frozen or corroded in place. In these instances the shaft would need to be removed anyway even if you had a cutlass bearing tool.

This article focuses on the removal of a cutlass bearing once the shaft has already been removed.

RANT ON:

Cutlass vs. Cutless®

Before we move on I should address the issues of the words cutlass vs. Cutless®. The word Cutless® is a registered trademark of Duramax Marine® LLC. It is a BRAND NAME for a sleeve or stave bearing.

Duramax purchased this name, and product, from Firestone Rubber many years ago. When Firestone developed the product they named it the Cutless®. Cutless® is a branded product name. People call soda “Coke” all the time, even if it is not the brand they are drinking.

Over time the marine industry began using the spelling cutlass perhaps because a windlass is not a windless, I don’t really know, but it happened. The long and short is that over time the word spelled cutlass has become an industry wide accepted generic term whether Duramax likes this or not. It is very tough to change history after it has evolved.

It should be noted that Duramax strongly disagrees with anyone using the term cutlass, with an “a”, as they feel it is simply too close to the word Cutless®, which is their brand of a stave or sleeve bearing. They feel using the word cutlass is intentionally misleading.

Duramax has been fighting hard to get anyone they can to stop using the word cutlass, including small time bit-players like me. When I spoke with them I made sure to mention the bearing I used was not one of their products. If I had used the word Cutless®, it would be false advertising and unfair to my readers. On top of that using the word Cutless® would be free advertising for Duramax.

I could really care less about the free advertising aspect, but if I did not use a Duramax bearing I am simply not going to call it a Cutless®. This is akin to re-filling Heinz Ketchup bottles in a restaurant with generic ketchup. It’s not Heinz, so why try to pretend it is… This bearing was not a Cutless®, so I am not going to call it one.

Duramax owns the rights to the word Cutless®, in many countries, though Australia recently shot them down because Australia believes the word cutlass is an accepted generic term..

The proper generic terminology for these bearings is stave bearing or sleeve bearing. So where’s the rub? Sadly the vast majority of boaters would not know what I am talking about, had I used the title;

“Replacing A Sleeve Bearing“

I chose the word cutlass carefully because it is well accepted, and understood by most boaters, as to what it is and describes. Had I physically used a Cutless® bearing then I would have used the word Cutless® but this one was not a Cutless® brand….

It should be noted that Vetus, a considerably larger world wide marine company than Duramax, continues to market their stave/sleeve bearings, even in the USA, as Cutlass bearings.

Here is yet another actual manufacturer or bearings calling them the accepted generic term Cutlass..

So, Cutless® is a brand name, & Duramax feels using the word cutlass is an infringement on their trade mark? Vetus, many magazines, marine chandlers, books, the country of Australia, and maritime history, all seem to accept the word cutlass as a generic term.

You the readers will have to decide whether to call it a Cutless®, cutlass, stave or sleeve bearing. I have simply chosen a term that is well accepted and understood by most boaters.

Do Quality Bearings Matter?

I prefer to use either Morse or Johnson Duramax manufactured bearings. I have found the consistency and accuracy of these product to be high of consistent quality. I have seen too many “generic” bearings not meet the spec size, come unglued from the shell, use a very low quality Home Depot grade yellow brass that completely corrodes quickly etc. etc.. It is simply not worth it to purchase a bearing from an unknown source or unknown internet vendor. Hamilton Marine in Maine is a great source for Johnson-Durmax Cutless® bearings. Vetus, Morse Marine, Johnson Duramax and Buck Algonquin (Buck’s are Duramax manufactured Bearings) are all what I consider reputable bearing suppliers.

I will give you one example of how the use of a cheap eBay sourced bearing cost an owner considerably more than he saved, lots more. A customer ordered a generic cutlass bearing and quickly realized the scope of the project was beyond his capabilities. He then hired me to remove the old one and install the new one. I don’t like to install owner sourced parts, but sometimes it goes with the job, and this is one of the reasons why.

When I got to the vessel the eBay sourced no-name bearing was under sized and not machined to standard industry spec for its “marketed” size. I had to decline & refuse to install the bearing, it was simply not safe.  I told the customer I could have one by the next day. He insisted on returning & getting another from his eBay supplier. Sure why not, it’s his money and he’s proud of his cheapness frugal nature, so I figured I’d let him play out his fantasy of saving money on eBay.

On trip #2 the next bearing came in, once again, undersized. Again, the owner insisted he would make this right after I basically insisted he let me source the correct bearing from a legitimate supplier and manufacturer. Remember, he has now been billed twice for travel/minimum charges only to stand there twiddling my thumbs to tell him once again, “it’s too small“. The third bearing he got was not even in the same league and so far off it was not even laughable. On that visit I suggested that he call someone else if he insisted on wasting my time.

At this point I asked him how much this bearing cost, seriously I really just had to know…. Very proudly he said; “Oh it was only $38.00 and “free” shipping.” Hmmmm it has now cost him over $275.00 in travel and minimum charges to save a grand total of………are you ready………. $8.99 !!!!!!!!! That is, the Johnson-Duramax Cutless® bearing I eventually sold him, was just $8.99 more than what he paid for his glorious eBay special. The Cutless® bearing fit perfectly and went in without issue. To save $8.99, the customer spent an additional $275.00, inclusive of multiple trips by me to his boat, for a removal & re-installation, that should have taken less than 2 hours in total.

Don’t be over-consumed by your penchant to save a few pennies, on a critical piece of gear, that needs tolerances tighter than unknown sources can apparently deliver. Please stick with brand-name known quality parts. Don’t be penny wise and pound foolish.

Cut Into The Bearing

In this photo you can see I have already made the cut through the bearing. The location of this cut is critical if your strut uses set screws. Some boats do not use set screws so the cut location is not as critical but on struts with set screws it’s far easier to utilize the set screw tappings to aid in breaking free the bearing.

The location of the cut should be opposite either the top or bottom of the set screw tappings. This way the bolts are pushing right at the bearing cut in order to split it inward. The picture denotes the optimum cut location of you have set screws. Without set screws two cuts 180 degrees apart make for easier work.

Making the cut can be done two ways:

#1 Cut it by hand with a hacksaw

#2 Cut it mechanically with a Sawzall.

I do not recommend using a Sawzall if you are not experienced in its use. Only use a reciprocating saw if you have the skill and ability to finesse it for this level of exacting use. If using a hacksaw, you simply remove the bade and insert it through the bearing then re-assemble the saw around the strut. Some folks suggest installing the blade upside down, but I honestly find it more accurate and easier to be holding the handle in its proper hacksaw orientation.

TIP: I recommend using Lenox hacksaw blades.

When making the cut for a set screw bend you do not need to cut all the way through the bearing but do cut evenly. You do however need to be about 99.5% of the way through the bearing shell or thinner than a piece of copy paper.

IMPORTANT: Applying more pressure on one end of the bearing than the other will result in an uneven cut. The saw blade needs to have 100% even pressure across the bearing in order to make an even cut. You want both ends of the bearing to become paper thin at the exact same time. If you do cut all the way through and score the inner surface of the strut it’s not a huge deal. If however you do this every time you change the cutlass it can get bad over time.

In this photo you can see that I have cut the bearing paper thin and not scored the strut in the process. I used a Sawzall with a very fine tooth metal cutting blade. I have lots of experience with reciprocating saws and feel quite comfortable with them. You’ll have to make that decision on your own. If you are in the least bit questioning your skill please use a hacksaw with a good quality blade like a Lenox.

Twist & Pull

Once you’ve collapsed the bearing inward, simply grip it at the bend with a pair of pliers and twist with the direction of the bend, as shown, while pulling at the same time.

Install Bearing

Installing the bearing is actually quite easy. It requires some threaded rod, use at least 1/2″, about four nuts, and some large and thick washers or sole flat stock steel with a hole drilled.

The most difficult part is actually getting the bearing started. You’ll want the bearing to go in perfectly straight so care must be taken to get it perfectly straight before beginning to tighten the threaded rod. If it goes in crooked it will bind and you can ruin the bearing.

You may want to lube the inside of the strut, and the outside of the cutlass, with regular Ivory soap in bar form, glycerin works too. Once the soap gets wet it dissipates and unlike grease or other lubes will not compromise the press fit of the bearing in the strut.

All Done

Press the bearing until it is flush with the end of the strut.  Re-install the set screws with blue Loc-Tite and you’re done.

IMPORTANT: The bearing shell should be “spotted” with a drill to accept the heads of the set screws. Please be very careful doing this. It is easy to go through the bearing wall and also easy to damage the set screw threads with the drill if it is not well centered. Just a slight dimple is all that is necessary.

Unless you own a hydraulic or mechanical press, like the Strut-Pro, the easiest and most reliable way to replace a cutlass is to do it with the shaft removed.

TIP: I recommend replacing a cutlass bearing any time you have the shaft out as they are cheap insurance.

This entire job, from start to finish, after the shaft was already removed, even with taking these photos, was about 30 minutes. If you need to make two cuts it could take slightly longer.

Good luck & happy boating!