Spare prop?!

[Eli27]

Hello all. So this question is about a spare prop! I'm big on have spares and also upgrading where possible. I would like to have a spare prop on hand just in case.

So instead of getting the same prop I thought maybe try something with a different pitch if it's been known to be better.

I have a 1979 albin 36 aft cabin trawler with a single leyman sp120 and no bow thruster. Most likely prop is the original. Anybody with similar boat put a different prop on for better performance? If I had a choice I would much rather have more control at slower speeds. I see a similar boat as mine with a 4 blade prop. What are the benefits and loses with different props?

As always your opinions are welcomed

 

[Gdavid]

Hello all. So this question is about a spare prop! I'm big on have spares and also upgrading where possible. I would like to have a spare prop on hand just in case.

So instead of getting the same prop I thought maybe try something with a different pitch if it's been known to be better.

I have a 1979 albin 36 aft cabin trawler with a single leyman sp120 and no bow thruster. Most likely prop is the original. Anybody with similar boat put a different prop on for better performance? If I had a choice I would much rather have more control at slower speeds. I see a similar boat as mine with a 4 blade prop. What are the benefits and loses with different props?

As always your opinions are welcomed

I assume you have a 3 blade since you are asking about a 4 blade (and 5 blades are unlikely to find on our type of boats). A 4 blade will tend to have better low speed thrust due to increased surface area, another benefit is that you can run a smaller diameter than a 3 blade and have similar thrust to a 3 blade, this is beneficial if you don't have much clearance the hull. A downside can be vibration at higher speeds when positioned closely behind a keel/skeg as 2 props are passing through turbulent flow at the same time rather than just one, which would be the case on a 3 blade prop. This really depends on shape of the keel and relative position to the prop, it may be a non-issue on your model. Hopefully, someone with a 4 blade on an Albin 36' will chime in.

 

[PM]

I had both for my 36 foot Albin. To be honest I couldn't tell a difference between the three and four blade.

pete

 

[jleonard]

I had a 4 blade on my 40 Albin which looks about the same but underneath as the 36. Never had any vibration problems so you likely won’t if you go that way.
I never ran a 3 blade so I can’t help with a comparison.
But I will add that if you’re going to carry a spare prop you might as well also carry the hardware,; key, nuts, cotter pin, and of course a zinc. If you are a diver then a prop puller and wrenches.

 

[jgwinks]

Can't comment on Albin but my Concorde came with a spare set when I bought it. When I got the spares out of the seller's storage one of them was badly bent up, so they did come in handy for him. He never bothered to have it repaired but I did. I carry them onboard and highly recommend having spares, with the needed hardware and a prop puller. It could take weeks to order a new one but a spare could be put on in a couple hours, even in the water.

 

[psneeld]

My advice would be based on your cruising grounds and type of cruising.

If in rocky areas, a spare is nice...especially if a nice used one is found before you need one. Saves a ton of money in many cases. It doesn't have to be a perfect match, just close enough to get you on the road again...

You don't even have to carry it with you if never on a tight schedule. Just leave it someplace someone can ship it to you or carry it to get going and have your prime prop repaired and shipped to where you need it or back home.

I did 20,000 miles over 10 years between NJ and Fl with a single engine prop with vary a nick so a spare for me would have been a waste. Sand/mud cruising bottoms are pretty friendly for protected props.

 

[Bacchus]

I looked for and found a damaged used prop. Had a propbshop I'd dealt with give me a $ for repair / rebalance and they even gave me a suggested value to offer the seller.
Seller took offer, even delivered it to the prop shop. Rebuild like new and everyone. Is happy. Don't be afraid to ask & trust a good prop shop.
Never needed it but very comforting having the insurance onboard.

 

[rslifkin]

You don't even have to carry it with you if never on a tight schedule. Just leave it someplace someone can ship it to you or carry it to get going and have your prime prop repaired and shipped to where you need it or back home.

Unless we're going somewhere remote, this has been my plan. I'm not changing the props myself in the water, so I'll be delayed waiting for outside help anyway. The props and related tools are heavy and take up a good bit of space, so there are likely more useful things to carry instead.

 

[Bacchus]

Unless we're going somewhere remote, this has been my plan. I'm not changing the props myself in the water, so I'll be delayed waiting for outside help anyway. The props and related tools are heavy and take up a good bit of space, so there are likely more useful things to carry instead.

My thinking is just the opposite but understand everyone sets their priorities.
I'm a single so prop is a key to cruising. I have changed my prop so know how but have no intention of doing it while cruising. Lots of marinas where we would cruise and with a short haul and spare prop the delay could be hours or a couple days max. Waiting for shipping & rebuild likely weeks. I guess if you are live aboard and live where ever you are... who cares.
How many carry spare belts, filters, etc... certainly they would not take nearly as long to obtain. I guess being a single my ER has enough avail space so why not?

 

[jgwinks]

Last time I sent a prop out for repair it took about six weeks to get it back. That's like a third of our boating season here in Michigan. The spare was already on the shaft so it didn't slow me down.

 

[O C Diver]

While I would encourage you to have the right prop as a spare, even a prop with a smaller diameter or moderately off pitch will get you back underway in displacement mode. See what your prop shop has for used wheels that will work. Or if you think you want to buy new, keep the original as the spare. Lot to be said for a short haul, prop swap, and getting back underway. Would much rather use my local prop shop than be stuck using one that may not do good work or charge a king's ransom because you're between a rock and a hard place.

Ted

 

[rslifkin]

My thinking is just the opposite but understand everyone sets their priorities.
I'm a single so prop is a key to cruising. I have changed my prop so know how but have no intention of doing it while cruising. Lots of marinas where we would cruise and with a short haul and spare prop the delay could be hours or a couple days max. Waiting for shipping & rebuild likely weeks. I guess if you are live aboard and live where ever you are... who cares.
How many carry spare belts, filters, etc... certainly they would not take nearly as long to obtain. I guess being a single my ER has enough avail space so why not?

If the space can't be used to carry something you're more likely to need (or more able to replace yourself), then I see no reason not to carry a prop. Shipping-wise, if we're still in the same general part of the country as home, then it's a couple hundred bucks to have someone run over to the house, grab the props, and overnight them to us, which isn't terrible in the grand scheme of boating.

 

[psneeld]

Repairs cost ya.... comin' or goin'.

If you wait and don't need/want to stay local to where the prop needs work...dockage, food, etc all add up fast...unless you enjoy where you are and waiting in a nice place is part of your plan.

A lot of places were you may ding a prop...you still have to travel quite a ways to get to a place to haul or you pay big bucks for a diver to come swap them.

That's why I decided on the no spare theory at all.... for bad vibrations, a decent diver (I know I could because I have done it on props for 40 footers or less) can bend back or pound/press out bends good enough to keep going at reduced speeds or at least go quite a bit of distance to get in a position for a whole new set of options.

I guess running vessels at less than perfect condition so many times just proved to me perfection on most everything (within safety margins) is over rated.

 

[rslifkin]

Repairs cost ya.... comin' or goin'.

If you wait and don't need/want to stay local to where the prop needs work...dockage, food, etc all add up fast...unless you enjoy where you are and waiting in a nice place is part of your plan.

A lot of places were you may ding a prop...you still have to travel quite a ways to get to a place to haul or you pay big bucks for a diver to come swap them.

That's why I decided on the no spare theory at all.... for bad vibrations, a decent diver (I know I could because I have done it on props for 40 footers or less) can bend back or pound/press out bends good enough to keep going at reduced speeds or at least go quite a bit of distance to get in a position for a whole new set of options.

Good points there. We did ding a prop last year very slightly. It was in a harbor, so I was maneuvering and had the stbd engine in reverse when we found some debris on the bottom. Slightly tweaked the trailing edge of one blade. Running at slow cruise everything was fine. No vibration, speed vs RPM was normal, etc. Tried to get the boat up on plane to test and then it became obvious we had an issue. Noticeable vibration and noise from significant prop cavitation, and the boat was much slower than normal. It was mid September when it happened, so we just finished out the season with a restriction of "slow cruise only" and dealt with it over the winter.



Rushing to install spares wouldn't have been worth it in that situation most likely, as we could easily wait until it was convenient to either switch props or have a shop clean up the damaged one.

 

[ksanders]

I've cruised a lot of sea miles in some of the remotest parts of the pacific coast of North America.

I do not carry a spare prop.

Why???

First off a prop is not all that hard to get if I REALLY need one. I know of several prop shops that keep new 24" D props in stock, and can ship with one to two days notice to get the hub machined out to my diameter shaft.

Second... I am not going to prepare for hitting rocks. Really??? That is not a foreseeable event, that is poor seamanship.

In Mexico the charts are not the best. But your eyes are your friend. Rocks don't just pop out of the ocean floor in the middle of nowhere. They are part of ongoing seafloor structure for the most part. So... stay clear of rocky points.

 

[kapnd]

I always carry the old prop that came on the boat, despite it being pretty badly beat up. I brought the boat home on it, but couldn’t run it over 1300 rpm without a noticeable shaking.
I go to some pretty remote locations, with nobody but myself to rely on if there’s trouble. It’s cheap insurance.

 

[Pascall]

I also don't see the point of a spare prop, the prop that is mounted with us is widely available from various suppliers.
Haven't needed it so far in 13,000 hours later, fingers crossed.
It is true that a 4 blade prop produces less noise than a two or three blade prop, which is also the reason why the prop has so many blades on submarines.

Mvg,

Pascal.

 

[jleonard]

I carried a spare in both of single screw trawlers. The one for the 40 Albin was 1 inch more pitch than what was on the boat. Fortunately I never had to use it. I also carried a puller and spare hardware.
Like carrying an umbrella just in case you need it.

 

[GB36_OuttaHere]

4 Blades on 135 twins

Love my 4 blade Michigan Wheels. Much better than the 28 year old 3 blades I replaced. 1988 GB36. Twin 135 Lehmans.

 

[Eli27]

I also don't see the point of a spare prop, the prop that is mounted with us is widely available from various suppliers.
Haven't needed it so far in 13,000 hours later, fingers crossed.
It is true that a 4 blade prop produces less noise than a two or three blade prop, which is also the reason why the prop has so many blades on submarines.

Mvg,

Pascal.

The main reason for asking the question was to see if people who had the 3 blade and switches to the 4 blade would say there was a difference in handling characteristics especially when docking.

I'm a single with no BT. That said I admit I'm not a boater of 30yrs. Especially single screw. I have driven many boats. Twins, singles, with and without BT, outboards. My main experience is I/O. Foe a few yrs 2 decades ago.

I don't consider myself a well seasoned boater who isn't afraid of going out on SCA days. But I consider myself more than capable of single handing any boat I decide to single hand. I know the basics of rules of the road. I know my nav lights and how to use then.

But, when it comes to possibly making a change like a prop,,, why not ask those who have more experience and have done it. Yeah, I can see why some would say it's dumb to have an extra prop but in times like these when you don't know how long something may take to get you might want to be ready.

And seeing that I would like to have a spare prop,,, why not experiment?

Best way to experiment with something that most likely other people have done is to ask those that have done the same.

Imagine walking into a prop store and asking "hhmmm I would like to know your opinion on 3 vs 4 bladed props?" Most likely they will sell me what makes them money.

Where as if I ask here maybe the response will be,,,,, dude, don't waste your money. Or it's actually worse or you won't gain anything on speed but low speed maneuverability increases.

Just looking for thoughts and opinions on 3 vs 4 blade props. Boats coming out anyway. Prop and shaft are coming out for service. If enough people say it's worth the change I'll try it. And if I don't like it,,,, next haul I'll spend 20 minutes switching the props and my 4 blade will be my spare. Easypeezy

 

[Pascall]

The designer, Ir. L. Huitema, who designed our boat, Barkas 1100, was way ahead of his time.
He was one of the few designers at the time who did everything in their power to make the ship as quiet as possible, we are talking about 1987.
He managed to get the maximum sound strength at 62 DB, which is very quiet.
His progressive design in terms of noise reduction was floating floors, panelling suspended in rubber dampers.
Multiple layers of insulation including (lead).
The hull above the propeller is fitted with (Weight) plates to reduce the noise of the propeller.
And use a 4 or 5 blade propeller instead of a 3 blade propeller, this to reduce the screw noise, this choice is made from thorough calculations, measurements/tests.
I will dive into the archives because I think there should be a test report with sailing with different propellers with the different values.

But, every ship is different, you only know when you try it or from experience of other people with the same ship and the same configuration.

Greeting

Pascal.

 

[AKDoug]

I carry a spare, too much of the boating season is lost if it's heavily damaged. I am a diver, and I carry a puller with me. If I had twins I think I would carry one spare, but I have one well protected prop that would actually take very bad luck to have damaged. It'll probably still be new and in the box when my boat finds a new owner, I'll be the first to admit.

I think a lot of it comes down to how common your prop is, a Willard has a 1 1/4" shaft which isn't very common. After ordering my new prop it still took several months to be delivered. Two months out of the summer season IS the summer season!

 

[PierreR]

The main reason for asking the question was to see if people who had the 3 blade and switches to the 4 blade would say there was a difference in handling characteristics especially when docking.

I'm a single with no BT. That said I admit I'm not a boater of 30yrs. Especially single screw. I have driven many boats. Twins, singles, with and without BT, outboards. My main experience is I/O. Foe a few yrs 2 decades ago.

I don't consider myself a well seasoned boater who isn't afraid of going out on SCA days. But I consider myself more than capable of single handing any boat I decide to single hand. I know the basics of rules of the road. I know my nav lights and how to use then.

But, when it comes to possibly making a change like a prop,,, why not ask those who have more experience and have done it. Yeah, I can see why some would say it's dumb to have an extra prop but in times like these when you don't know how long something may take to get you might want to be ready.

And seeing that I would like to have a spare prop,,, why not experiment?

Best way to experiment with something that most likely other people have done is to ask those that have done the same.

A cheaper way way to experiment is to first get a copy of Dave Gerr's propeller handbook. Written for the knowledgably amateur to understand propellers. With knowledge you will then nail down what you want with fewer expensive trials.

When I pulled my boat for the winter I noticed that I have two different blade designs on my twin engine boat. Props are the same diameter and pitch. The opposite pair are bolted to the wall in the rudder room along with two shafts. I am studying the book to determine which set is likely the best for my boat.

Yes, I am carrying two spare props and two spare propeller shafts everywhere I go. I'm certain that the reason I have never dinged a prop is because I carry these spares. So, should I remove some of the lead ballast to compensate? Ballast is probably needed when not carrying 5,000 lb of fuel and 2,000 lb of water in a 42' boat.

The book will tell you that for equivalent thrust, the four blade will be less efficient than the three blade. The four blade being less likely to cavitate at higher rpm's with a smaller diameter, so better for higher speed boats. Vibration varies by underwater boat design and maintenance.

 

[SteveK]

I prefer to have a spare engine which comes complete with a spare prop.

That said my current boat came with two spare props that look to be spares for many years, maybe even since the boat was new. Petina.
I also keep an eye out for underwater obstructions, and knock on wood, have never damaged a prop.

 

[mgreen]

Torsional analysis report

Blade count along with all aspects of the physical properties of the prop, along with the shaft diameter and length, gearbox tooth counts and piston count and vee angle would all have been part of the TAR, if one was done. One of the goals is to not allow the full system to have harmonics. Changing any one piece can set up annoying or damaging harmonics. Or usually not. One would hope that the design team took this into account. I would want to borrow a test prop myself if possible if I was buying new. A get used home prop is a different story.

My boat came with a spare. I hope to never use it but I will carry all the spares I can, along with the required tools that are needed. I am pretty handy and do as much of my work as I can. I feel that my likelihood of getting something repaired goes up if I have parts and specialized tools available, even if I have to hire someone for something I can't do. I can swap my own prop, and every other spare I currently have. But on more modern engines I can see that my talents could fall short.

 

[Capt Ray]

My prop shop guy recommended having a spare prop aboard for our Great Loop trip May 2021-May 2022. According to him, it may take weeks to get a new prop, or weeks to get one repaired, and I tend to believe him. Because when I tried calling around the country, these are NOT readily available items with the perfect match.

My prop shop guy also said, "If you find one "close" to the same specs, buy it! if the price is right." "At least you have something that can keep you going rather than being stuck for a month or two (or more)." Shipping these things is expensive too!

He had one commercial customer on Long Island NY, where the revenue season is short, who lost more than half of his annual revenue waiting for new props.

To find a good deal, take your time and search ALL the online sources. eBay, Craigslist, and all the vendors. In time you may get lucky and find the right deal.

CURIOSITY, EXPERIMENTING & LEARNING

I bought our MS 390 with a 26x27 RH 1-3/4" 4-blade on it.

I found a 27" 3-blade prop 1-3/4" shaft and I think the pitch is the same or a maybe a 28" pitch... I don't have it written down anywhere here. Used, but in fantastic condition. Found it on Craigslist. Some full-time flea market buyers picked it up somewhere. I drove 6 hours in each direction to pick it up. But it was just a few hundred dollars.

I know my spare will "fit" ... and I actually look forward to experimenting with it to see how it performs. "It is how we learn!" So the next time I take off the 4-blade original, I'll put on the spare and have some fun experimenting.

One simply needs to know what max RPM one's engine should be cruising at.

We are slow trawler... so I'm not too worried about "top end performance". But I am interested in fuel economy for the long haul, as we follow the seasons north and south on the east coast now.

 

[Darlin]

Contact Ron Kruger of Olympic Propeller, Anacortes, WA. Some years ago he recommended a larger 5 blade prop for my twin 120 lehman OA 44. Less vibration and .5 knot better speed at same rpm.

 

[ronobrien]

I assume you have a 3 blade since you are asking about a 4 blade (and 5 blades are unlikely to find on our type of boats). A 4 blade will tend to have better low speed thrust due to increased surface area, another benefit is that you can run a smaller diameter than a 3 blade and have similar thrust to a 3 blade, this is beneficial if you don't have much clearance the hull. A downside can be vibration at higher speeds when positioned closely behind a keel/skeg as 2 props are passing through turbulent flow at the same time rather than just one, which would be the case on a 3 blade prop. This really depends on shape of the keel and relative position to the prop, it may be a non-issue on your model. Hopefully, someone with a 4 blade on an Albin 36' will chime in.

I have a 1973 GB36 with twin FL 108HP and 4 blade props. 17X22. I have only run it once after purchase before taking out for a multi-year refit. On sea trials we ran it at full throttle into a 4-5' chop and there was no vibration what so ever. If you want to contact me I will send the spec sheets on the props.