Prop replacement

[Triumph]

I don't know the answer to your question. I looked, and I don't see my notes about which props we tested. There were three, the third being the 14x10 and the winner. I do not believe they were pitched any more than the 14x10, probably less. The increase pitch over this could harm your transmission if it is beyond what is recommended. That's what you need to check out. Otherwise, it may be a good thing.

Bill
TRIUMPH

[Outlander366]

Yes, there has been a lot posted about the issue with the prop making noise at higher RPM and the boat not going into chop well with the original prop. The original prop was called a "sailor" prop by the manufacturer. It's blades were not as wide as a normal prop. About 3/4" more narrow. This is the problem. Too little prop for too much boat. You need wider blades on the prop. The one Catalina suggests works well. It's got a good pitch, and wide blades. I've been running on it now for years as have other C350 owners and this pretty much solves the issues you mention.

PS. I was the guy that did the test of props for Catalina when we were looking for the right prop.

Bill
s/v TRIUMPH

Hi, I'm the new owner of hull 366 and I'm just learning the handling of this Catalina 350. Coming into my slip that has a starboard finger pier is very exciting when I shift into reverse as well as leaving the slip, although I'm able to fend off a post on the port side to counter the prop walk.

Bill, I read that you tested the M 14x10 prop. My question is does this prop do anything to reduce prop walk or did it just work to solve a cavitation problem.

George
S/V Outlander

[Triumph]

Only addressed the cavitation issue.

Bill

[Capt. Nini]

Sorry it has taken me so long to furnish details of the EWOL Feathering prop that I purchased in December 2017. I have been battling health issues that prevented me from testing the prop.

See 5 December and 6 December post.

I have a 16” wheel set at 17* which equates to 9.2 inches.
Took the boat out yesterday conditions varied. In smooth water with 12 kits. head wind I achieved 6.5 kts. STW and 5.9-6.2 kts. SOG at 2400RPM.

Reverse power is as instantaneous as in forward. Prop walk is about like the fixed prop, not enough experience to tell for sure. Don’t have light wind feathered prop stats yet.

It is hard to quantify, but under sail in 12-15 kts. wind, I felt like I had better performance.

[rjengelhart]

Hi. Anybody using Gori props...2 or three blabed?

What sizes?

Thanks.

[sargentef]

We put a gori 3 blade on ,15x9. Great prop, no prop walk, 6.5 kt.@ 2300.

[sargentef]

However, our fuel consumption has gone up!

[wolfe10]

However, our fuel consumption has gone up!

Look at the exhaust. Any black smoke (indication of over-fueling)? Yes, being "over-proped (too much diameter/pitch/# of blades) can cause this.

If so back out of the throttle until the black smoke just goes away. If you can run just under "starting to give black smoke" are you are OK. If not, may need to reduce diameter/pitch.

On edit: Had a private message asking how being over-proped could cause black smoke. OK, if the throttle is at or close to WOT (Wide Open Throttle), it is fueling enough to run the engine several hundred RPM faster than you are able to obtain. BUT, you are not taking in enough air to burn that amount of fuel-- the engine is "breathing less". Think of the engine as an air pump into which fuel is injected-- every second time each piston goes down, it draws in air through the intake. Lower RPM= less air flow. So, too much fuel for the amount of air- smoke.

[TBOT422]

I finally had the opportunity to do some testing over the last week. Bottom was freshly cleaned. Out of gear our governed WOT RPM is about 3100 to 3200 RPM. After motoring for most of the day, while running in gear at 2400 RPM, went to WOT. RPM instantly went to governed RPM. That implies the boat is under propped per Brett's procedure. Since we have hull #422, and the letter from Jerry Douglas implies that all hulls after 400 were supplied with the Michigan M Series 14x10 prop, I assume that is what we have. I'm not sure where to go from here. My main goal is to increase boat speed when under power. Any suggestions?

[wolfe10]

Agree, you can use more prop.

What is your boat speed at 2,400 RPM smooth water? At WOT?

[TBOT422]

I've not done any accurate speed tests. My guess is that we average around 5 knots at 2400 RPM. Sometimes 5.5 sometimes 4.5 depending on tide. A really strong tide and we can see 6 knots, but also have times when we can't get 4.

I have no idea what top speed is at WOT as I've never ran at that speed long enough for the boat to accelerate to a fixed speed.

From what I am reading, the Flex-O-Fold 15x10 may be over-propped. But I don't understand if that is a problem if you never run near WOT. If you are slightly over-propped and keep RPM below the "black smoke overheating" threshold wouldn't you be achieving your best speed possible?

As long as you are under propped you cannot reach an optimal speed even at WOT. Correct? I assume that cruising at 2000 RPM at 6 knots is better on the engine than cruising at 2800 RPM to achieve 6 knots.

We have the Universal M-35B and Hurth transmission that I believe has a ratio of 1.88.

[wolfe10]

When discussing props, please specify 2 or 3 blade-- BIG difference.

Yes, the the Flex-O-Fold 15x10 three blade is over-pitched. Good boat speed for RPM, but one has to be careful/be aware of smoke to not overload by trying for too high an RPM. Keeping engine running at its best (valves adjusted, clean air "filter", clean fuel and clean fuel filters, etc) helps.

Said another way, with a knowledgeable operator, an OK choice.

Would see if anyone is running a Flex-O-Fold 15x9 three blade and what their experience is with it.

[TBOT422]

How about this reply from FlexOFold. This has me really confused and a little scared. If many of the owners on this board seem to think the 15x10 is overpropped wouldn't 15x11 be even worse? Can there be that much difference in engines or transmissions or has FlexOFold changed their design slightly over the years?

Thank you very much for your inquiry.

With a Universal M35B ( max. rated 35 hp / 3000 rpm, gear reduction ratio 1:1,875 ) we would recommend a 3-blade 15x11-3R propeller for your Catalina 350.

The price for a complete 3-blade 15x11-3R Flexofold with hub for ISO / SAE standard shaft is USD 1975,-

http://flexofold.com/folding-propellers ... propeller/

Price is incl. shipping costs with a door-to-door service by UPS from Flexofold in Denmark to the address in the USA. Possible local import duties are not includet!

Prices are valid 4 weeks.

If you wish to order, we kindly ask you to return this e-mail, stating your delivery address whereafter we will return with an order confirmation / proforma invoice with link to payment by credit card.

Shipment can be made approx. within 3-5 days from orderdate and registration of your pre-payment.

There is a 3 years warranty on the complete propeller, however, product life warranty on the shock absorbers!

You can find detailed informations about the choice of the propeller, references, installation, warranty etc. on www.flexofold.com

Looking forward hearing from you soon again.

Best regards,
Nina von Bergen
Export Sales

[wolfe10]

I agree. Makes no sense.

[TBOT422]

Brett,

Referring to the M-35B Service Manual, it shows the M-35B rated at 35 Hp at 3,000 RPM. Cruising Hp is about 20 Hp at 2400 RPM. It also shows the M-35B to have the Hurth HBW-100 as standard with a gear ratio of 1.79:1. I am nearly positive that our boat has the Hurth HBW-150A with a gear ratio of 1.875:1 as I recorded the part No (ZF 15MA) off the transmission a long time ago along with the Part No and serial No. Per the M-35B Service Manual the HBW-150 is normally supplied with the M-40B.

Would the higher gear ratio of the HBW-150 necessitate or accommodate a higher pitch for the prop? I assume that if the transmission ratio is 1.875 versus 1.79, the prop is turning about 5% faster at the same engine RPM, correct? 3000 x 1.79 = 5370 RPM. 3000 x 1.875 = 5625 RPM.

Edit: I assume that if the transmission ratio is 1.875 versus 1.79, the prop is turning about 5% SLOWER at the same engine RPM, correct? 3000/1.79 = 1676 RPM. 3000/1.875 = 1600 RPM.

Thanks

[wolfe10]

Sorry, boat is in Florida, we are in Texas, so can't confirm transmission, gearing, etc.

Just first hand experience with 2003 Catalina 350 with stock engine and transmission.

[TBOT422]

Response from Flexofold, the Plot thickens:

if you have a gear reduction ratio 1:1,79, you´ll need a 15x10-3R propeller,
if you have a gear reduction ratio 1:1,87, you´ll need a 15x11-3R propeller.

If the gear reduction is higher, the propeller turns slower and needs to be larger/ more pitch.

But I have never seen the 1:1,87 gear reduction at this engine, so you better double check. There has to
be an information plate on the gearbox.

Best regards,
Nina von Bergen
Export Sales

[cuthbert]

I looked at the flexofold prop and had a similar size recommendation from their sales team after some to and fro on the exact markings of the transmission FYI mine is a marked Model – ZF 15 MA serial number 27975 part number (difficult to read) 332500100
A = 1.88 B =1.95

If you do go with this please post the results, I assumed looking at the pics that the flexofold mounted has the blades slightly further back and hence the cavitation issue is not exacerbated but was reluctant to be the first to drop 2K in order to find out.

[TBOT422]

Yep, We have the same transmission.

Transmission Label.JPG (59.73 KiB) Viewed 6075 times

I'm still not sure that I want to go with the 11 pitch prop, but I do understand the rational that the prop is spinning slower with the 1.88 gear reduction. I am just surprised that a 5% change in prop speed would require or accommodate a 1 degree increase in pitch.

What I am wrestling with is if I were to assume that the 15x11 prop might be over-propped, what problems or issues might it create if I never operate the engine anywhere near WOT? In 8 years, I doubt I have ever exceeded 2800 RPM for more than a few seconds, and generally run around 2400 RPM. Catalina recommends a cruising RPM between 2000 and 2500 RPM. From what I understand, if the boat were over-propped, it would tend to overheat and have black smoke at high RPMs. What I don't understand, does it have any impact or effect at lower RPMs? My thinking is that changing the prop diameter and pitch simply changes what one might refer to as 'high RPMs'. I think of it in terms of motor-sailing. Suppose you are in light wind and need a little 'iron-genny' to make reasonable way. If you are under-propped, you might run at 1500 RPM to get to your destination. Whereas if you were over-propped, you may only run at 1200 RPM to make the same speed. Isn't that a good thing? I don't really understand sizing a prop for WOT performance when you don't operate at that level. I suppose if your mode of operation is to always 'put the pedal to the metal', then sizing the prop for those conditions would help prevent you from destroying the engine.

If I thought that there was a fundamental issue or problem with being over-propped at lower RPMs, then I would go with the 15x10, but if the problems only exist at 2800-3000 RPM, then the 15x11 may be satisfactory for my situation. If your choice is to over-prop, or under-prop, it seems to me that over-prop is the only choice you have to be able to achieve your boat's maximum speed. Of course, you have to control the throttle to keep the engine from being over-stressed. If you select a choice that leaves you slightly under-propped, you can not achieve your maximum speed even if you are running the engine at WOT. But then, I don't know much about boats or engines. So I may be missing something.

[cuthbert]

I noticed recently one thing that seems to exacerbate the prop cavitation issue is the sea state. I have the original prop and it has never been an issue as I'm mostly using the ngine for just leaving the marina or motor sailing home on dead calm mornings before the wind picks up always running around 2k to 2.4K to get 5-6 kts and over the years tracking fill ups the fuel consumption has been 2 to 2.5 hours per gallon. I should add that WOT from 2200 rpm gives a few seconds of cavitation and extended runs (more than a minute or two) above 2400 rpm will lead to some heating of the exhaust as there is visible steam after a while even though the temp guage is steady at just over the mid point (which I think is approx 170 from memory).
However I just did a long run on the engine (4 days) coming back from the Baja peninsula and heading into a swell meant that the boat had to be tacked on a course to not take the swell head on, as the moderate (not uncomfortable but noticeable) swell caused this partial cavitation over the top of every swell at 2200 rpm or above. The best/optimal was 2100rpm and that gave me 4.5kts or so (difficult to be precise as there is always an element of assistance from the wind over a partial main sail) at a 30 degree offset to the swell, averaging on the journey 1.7 hours per gallon. It did put the prop issue back on my to do list. I have contacted Catalina (no response so far) about upgrading the original prop and if they have stock will they offer a price on the 14" prop. If I can get one for a few hundred I would make the change next next haul out. Has anyone got the 14" upgrade deal in the past few years or was it a bit like the fridge problems where they took action around the time of initial awareness and then it died on the vine?

The alternate is to go with a folding prop. Being a west coast boat it only gets hauled every 3-4 years and so hauling out is a bigger deal than NE boats. Also since I don't race and even tow a dinghy when sailing a lot of the time to Catalina island the performance isn't paramount. But that leads back to paying some manufacturer for a best calculation/estimate and that just isn't as good as some prior experience/practical knowledge (after all it looks like Catalina went through some testing with many owners before going to 14" props).

Last year I did a (big ship) cruise and one nice old chap on my table was a prior boat owner of many years and experienced Mediterranean sailor and on this subject he said "nothing complicated under the waterline, it's just trouble". Food for thought.