Propellers for 33 with 3208T

[DemianM]

My dad hit something underwater during the weekend, and one complete blade is missing from the starboard prop. I need to source one or two propellers, where can I buy them from? I have tried hightide, but there they are around 800 each. Any other place where I could get them a little cheaper? If anyone has a spare set willing to sell, please let me know! Thanks Demian

[dougl33]

If its nibral (which it should be if its a diesel boat) then $800 is a good price for a brand new prop. You can try Ebay or do an internet search for used props. That being said, I would never buy used props. You have no idea what the prop has been through before you got it. You can only mess around with the pitch so many times. Go new. A new set of Michigan nibral 3 blades (DJX) will make a big diference in how the boat performs.

[schultz]

I agree with Doug, go with a new one. For a comp try calling Acme Propellers at 888-661-2263.

[BECCA ROSE]

I got mine from General Propeller in Bradenton, Fl. 800-282-3181 They were 1,300 a piece for 3 blade DJX Nibral. Don't buy used, I know at least 2 people that have thrown blades by buying cheap used props. If I had to guess, I think they're is a lot of very poor quality used props for sale. You can talk General down a little on the price if your persistant. Are you sure he hit something? Maybe you just threw the blade, makes a hell of a sound when it goes. Thats what Doug told me anyways.

[DemianM]

Thanks a lot for the replies. Well, my dad swears to me that he did not hit anything, so I guess he might have just threw a blade as you all say, I did not know that this could happen without hitting anything. The vibration and noise was TERRIBLE he says, it felt like a massive breakdown. He had to limp home at about 800 rpm. What specs should I be looking into for the props? My boat is a 1981 33 FBC with 3208T 260 hp engines. I can assume the engines (which were factory installed) might not be running at 100% efficiency, though. Should I go for a lower pitch? The boat is used on fresh water.

[IRGuy]

Demian... There is a simple way to determine if your props are the correct pitch and diameter for your boat/engine/transmission combination... With the boat normally loaded and the engines at normal operating temperature, push the throttles all the way forward and after things settle down look at the tachometers of both engines. Engines with the correct combination of transmission ratio, prop diameter and prop pitch should be able to run at somewhere around 200 RPM above the RPM they are rated at. If they don't, and run at a lower maximum speed you are most likely "overpropped", meaning the props have a combination of too much pitch or too great a diameter, and are overloading the engines. This results in shorter engine life.. an expensive situation. If the engines turn faster than about 200 RPM over rated speed the engines are not being asked to put out their maximum power, and you can increase prop pitch and diameter somewhat. Obviously, the second situation is loading the engines less, and while engine life might be optimized, there is more boatspeed available to you. As an example my engines are rated at 2,800 RPM. During the seatrial when tested as above they turned between 200 and 250 RPM over 2,800, meaning the combination of transmission ratio, prop diameter and prop pitch are correct, and engine loading is what the manufacturer specified it should be. Hopefully someone here with Cat 260HP 3208 engines will tell you what props they are using, and what max RPM they can achieve with them.

[dougl33]

Demian, If your Dad's boat has a 1.54:1 trans ratio then I'm pretty sure it came from the factory with 3 blade 20Dx22P with a cup. I've got Michigan 3 blade DJX nibrals and I love them. Very smooth. I threw a blade back in 2004 or 2005. I had gas engines back then and was cruising at 19 knots (3100rpms) when there was a tremendous whack and a sh!t load of shaking. I was in 200 feet of water at the time and thought I must've hit a submerged container and was sure I had to be taking on water. I was surprised to jump into the engine room and find it bone dry. On the long ride home I went through all the scenarios and the only conclusion I could come to was that I had thrown a blade. All of the old timers at my club thought I was crazy, but after limping home at 8 knots (which was miserable) I hauled the boat to find that the port prop was short one blade. It had broken off right at the hub. Bill Dunlop had the same thing happen to him crossing Nantucket Sound back in 2008. Both sets of props were used (mine came with the boat and I had had the pitch changed). If you can buy a used set that you can confirm have never been changed then you'll probably be OK, otherwise I'd go new.

[BECCA ROSE]

If one threw a blade, the other is probably right behind it. Get 2, then you won't have to worry about them for a long time.

[DemianM]

Thanks again for all the replies! Frank, the propellers I had where spot on, running about 200-300 rpm over specified RPM, thing is, I dont know which pitch these propellers are, so now for ordering I just dont know what to order, but most are set on a 20Dx22P prop, I think I will go for the DJX props in that pitch and size. Doug, I think our boat has the 1.54 ratio, not sure though but I see no reason for it to have another ratio...was it common back in the day to put different ratios? Our boat has the twin disc MG502 transmissions. Which diameter should the shaft be? Other than diameter, is the conical part of the shaft standard? I dont want to mess up on ordering! My idea is to get a set of new propellers, and keep the old one for emergencies far from home. I will now call these places that were suggested for a quote, thanks a lot! Demian

[dougl33]

Well, I've got 2 spec sheets (1984 and 1987). They both list the Cat boats as having the MG502's with 1.54:1 ratio and inch and 3/8's shafts. I've only heard of one factory Cat boat having inch and half shafts (Frank Bryson's boat). All others have been inch and 3/8's. I'd say its safe to assume you have the stock set up. All you need to tell them is shaft size. Aren't there any markings on the old prop? Make sure you order nibral. As far as Acme or Michigan, I run Michigans and I tried Frank Price's Acmes. There was no measurable difference. I'd go with whichever one you can get cheaper.

[DemianM]

Hey guys, I just talked to the person who is making me one new prop here (I will keep the ones that are now on the boat as spares) and he says that my actual props are 21Dx22P .... and my boat is reaching well its WOT rpms, going about 3100 rpm. I think I will go overrevs if I go with the factory 20x22, what do you think? For what it´s worth, I have no genset onboard and the boat is run on fresh water. Thanks Demian