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1

Main Message Board / Re: Prospective Owner Questions

« on: June 09, 2019, 03:15:13 PM »

My ST4000 autopilot failed on my maiden voyage after taking ownership. I disassembled the wheel mechanism and the belt was shredded where it makes the tight wrap around the motor sprocket. I think this is common if left unused for a few years.

Raymarine has discontinued the belt for the original ST4000, but perfectly fine replacement belts are readily available on ebay. I bought two so I'd have a spare. It is a very easy fix:

https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=belt+raymarine+d169&_sacat=0

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Main Message Board / Re: Urgent: Sourcing a new strut

« on: April 28, 2019, 06:08:01 PM »

By the way, I applied my insurance company's prop allowance toward a Flexofold prop. Prop was ordered Tuesday, and arrived Friday. So AFAIK, all parts are here (strut, shaft, prop, packing box).

I looked at a few of the flexible coupler options described here, but decided to let them just do a like-for-like replacement on that part (one-piece solid steel coupler). I did't want to complicate things for the yard too much beyond what I've already done with the unfamiliar prop design.

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Main Message Board / Re: Urgent: Sourcing a new strut

« on: April 28, 2019, 05:41:39 PM »

Pictures taken today, after shaft/strut removal and receipt of some parts:

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Main Message Board / Re: Urgent: Sourcing a new strut

« on: April 28, 2019, 05:40:07 PM »

More pics from post-damage survey...

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Main Message Board / Re: Urgent: Sourcing a new strut

« on: April 28, 2019, 05:38:09 PM »

Thanks for all the advice. It's real helpful. I'm not going to micromanage the yard pro, but he did ask my advice on the hole positioning issue for the strut, so I'm going to advice him pretty much along KWK's line of reasoning. I'm heading out of town on business in a week, and he's not going to have it done before then, so I'm looking at two more weeks before repairs are complete. I'm not going to hassle him over that, because I want it done right and not a rush job. It's clear from the things I see changing every time I go there that he's "getting his ducks in a row" to start work, and he also needs to prepare an updated quote for the insurance company before starting work.

I went down to the boat twice this weekend to check things out and re-measure some stuff. The strut/hull holes are all VERY close to the correct position - like within about 1/8". I think it will be much easier to move the holes in the boat than in the bronze. The new strut's flange is definitely too wide and will need to be tapered a bit. When you look closely at the original strut, it's clear that it was also manually tapered to fit within the little "keel" that's built into the hull there.

Why do you need a new strut?

Severely bent during impact with submerged log. Based on the ~8"x8' cross section I saw churning around behind the boat after the impact, it was a railroad tie.

Any pics of bent/damaged running gear parts before replacement?

See below. Some of these pics are from the original haulout, and some are more recent after the removal of old shaft/strut and receipt of the new parts:

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Main Message Board / Re: Urgent: Sourcing a new strut

« on: April 27, 2019, 08:26:59 PM »

Hi all,

The strut arrived from Catalina Direct, and it is a close, but not perfect, fit. The pre-drilled holes on the strut are about 1/4" further apart in all directions than the prior strut. Also, the strut's flange is a little too wide at the aft end, and will not allow enough space for any fairing or gelcoat without some trimming of the bronze flange. It looks like the original strut may have been trimmed in a similar way.

The guy at the yard who is doing the work said it may add a few hours of labor, and we agreed that I would check with you guys for suggestions on the best way to proceed.

First of all, I should mention that the strut that we received from CatalinaDirect does not have the raised "CAT 34/36" letters on the port side of the casting as pictured on their website (Neither does Noah's):



Interestingly, the original (bent) strut that was pulled off my boat does have those raised letters. This suggests that CatalinaDirect might have changed sources for this strut since the time they took their pictures.

Regarding narrowing the aft sides of the flange, I assume that this could be easily done by tracing the shape of the old flange onto the new flange, and grinding the metal off the sides using a rotating bench grinder.

Regarding the misplaced holes, the question is whether to enlarge the holes on the strut, or perhaps enlarge the holes in the boat. The locations are really only about 1/8" or so off for each hole, and the bolts from the original strut did not go straight through the hull. The lock nuts and glassed-in backing washers inside the hull are actually further apart than the holes outside the hull, suggesting that the bolts were angled out somewhat from the strut holes. So with the new strut's holes further apart, it might be possible to leave the backing washers in their current place inside the hull and just "cone out" the holes in the hull a little bit to allow the bolts to penetrate the hull at a different angle from the pre-drilled holes on the strut. Obviously, sealant would be called for in the enlarged holes, and of course, fairing compound and gelcoat would further help to seal the whole thing off. I think that this would be better and quicker than trying to expand the holes in the metal. But it all must be done carefully to preserve the alignment with minimal adjustment of the motor mounts.

How does this suggested procedure compare to others who have done this project? (Noah?)

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Main Message Board / Re: Urgent: Sourcing a new strut

« on: April 20, 2019, 08:20:37 PM »

I though I'd close the loop on this, since I've learned some interesting things since I last posted that will be of interest to anyone else who needs to source a strut in the future.

<<However, I realize it's also possible that Buck Algonquin might have an identical one to the Catalina/CatalinaDirect, and might even make it for them. >>

Why not ask CTY parts, should be the first go-to for parts.

Alternatively ask BA if they supplied the strut to CTY.

I finally found the phone number for Buck Algonquin and called. The guy said they didn't make a strut for Catalina 34.

Then I called Catalina Yachts, and they told me they no longer carry struts because they had gotten rid of them in all their current boat designs. He told me that Buck Algonquin made them for Catalina, and I should call them. (Go figure!)

So I called the guy back at Buck Algonquin to tell them what Catalina told me. He told me he's only been there a few years, and hadn't heard of any struts for them, but there's another guy who has been there for 20 years who would know. Unfortunately, he's out until Monday or Tuesday. I asked if there's any chance they had them in stock, and he said that if they did he'd probably know about it, so I'm most likely looking at 5 to 7 weeks to have one made.

I wasn't going to wait half a week on such a long-shot chance, so I called CatalinaDirect, who had four in stock, and the part will arrive on Monday. I suspect they get them from Buck Algonquin (which is in Stevensville, MD, only about an hour away from my boat), but it's quicker to get it from California.

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Main Message Board / Re: Online prop sizing calculators

« on: April 19, 2019, 06:11:33 PM »

Noah and I had a good talk on the phone today. His experience is very helpful.

Guys : I have tried to get a logical explanation to "no avail", of why Catalina's OEM 3 bladed prop is a 15"x 9" for a 21hp engine C34 and the SAME for a 35hp engine C34???  It's like HP is not a factor?!?

Here's a logical explanation why lower pitch may be a better fit for the more powerful M35B motor, although it admittedly fails to explain why Catalina didn't use a higher pitch on the older boats (which seem to be working very well with 15"x10"):

Horsepower is a big factor, and that's why the 35 HP M35B/HBW100 has a more aggressive gear ratio (1.79:1) than the earlier 21 and 23 HP motors (2.05:1). At a given motor RPM, the M35B's transmission uses the motor's greater torque to rotate the prop 15% faster (1.79:1 reduction vs. 2.05:1 reduction). Since our boats all have the same 29.8' LWL and therefore the same 7.3 kt theoretical hull speed, a prop of a given diameter and blade shape that's spinning 15% faster with the M35B/HBW100 will "screw" the same distance/speed through the water with a 15% lower blade pitch. So the M35B powertrain is properly matched to the boat's hull speed with a 15% lower pitch prop. Attempts to put a more aggressively pitched prop on the M35B powertrain will accomplish little other than preventing attainment of full spec RPMs because the boat cannot plane - it will just dig its stern in the water as it tries to "climb out of the hole". So all you guys with older, less powerful motors can stop scratching your heads over this. Just because your 15"x10" or even 15"x11" prop works well for your powertrain does NOT mean that it will work on the MkII boats with more power motor and more aggressive gearbox. We spin our props a lot faster. As a first guess, I'd take any prop that the older motors are spinning and reduce its pitch by 15% for the M35B/HBW100.

I've read as many comments on this as I can, and can see that many older boats are seeing success with the higher pitched props. Some MkII owners are also happy with 15"x10" props. But it looks to me that among those who are not happy with 15"x10" props, virtually all seem to be with the M35B/HBW100 powertrain. I believe that my above explanation is why. I don't have time to go back and re-read everything I've seen over the last several days, but here is one example:

John Langford, MkII boat: https://c34.org/bbs/index.php/topic,8715.msg62337.html#msg62337

When I used the 15x10 configuration on my new flexofold the stern submerged at my normal cruising revs of 2200 rpm and I couldn't get to 2900 at all.  For the MK II at least, 15x9 is the right combo. It's a great prop in forward and reverse. 

I think there's another example that just posted while I was writing this.

There is a lot more to a prop's design than just the blade pitch. The Flexofold props, in particular, have been shown to generate significantly greater speed than other props at a given RPM (see the famous Yachting Monthly tests). https://www.yachtingmonthly.com/gear/folding-and-feathering-propeller-test-29807  That just doesn't happen by magic. If a prop is giving more speed at the same RPM, it is going to have more resistance against the shaft's torque, and result in lower RPMs at full throttle. So in my case, where I'm planning to replace a "skinny blade" original Sailer 15"x9" prop with a Flexofold 15"x9", I think the Flexofold's blade design is going to lower my maximum RPMs even if I stay at 15"x9" blade pitch. I do believe that 15"x10" might fail to achieve full throttle RPM of 3000 per Universal spec, so I am gaining confidence in my choice.

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Main Message Board / Re: Online prop sizing calculators

« on: April 18, 2019, 08:08:57 PM »

Breaking : The boat builder dictates the prop diameter - to prevent "buffeting" from the blades against the hull.  Very Important!!

BTW, the 3 bladed Michigan Wheel "sailor" props that I have seen, have much large blades (blade cord) than the Catalina 3 bladed "sailor" props!!!!

You need to read my Mainsheet tech note article on "Prop pitch/size and Boat Speed!!

A few thoughts

I have no intention of ever getting a different diameter prop than 15". I was just citing the crazy 17"x11" result that Michigan Wheel's calculator spit out.

I've read your Tech Note several times over the last few months. Very helpful, but there are no absolute answers, especially since there are so many variants on motor power and gear ratio. Also, there are some people with different goals. I see a lot of comments from people who are only able to get 2800 RPM at full throttle, but are thrilled with their performance at cruising speed. I see some who increased pitch and worked fine at first, but lost speed and/or gained heat as the season wore on. I'm not willing to accept full throttle speed under 3000 RPM (I want that reserve power if I ever encounter really strong headwinds), so I'll probably stick with 15"x9" for my next prop. I get decent speed at 2200-2400 RPM all season long, and great fuel economy, so I'm not going to risk higher pitch.

I agree that Michigan Wheel has changed the design of their Sailer props. The really early ones like came on our boats have very skinny blades (low E.A.R.), but the newer ones have fatter blades (higher E.A.R.). There are a few pictures on their website showing the thinner blades, but all the product listings show the new props, so I assume the older ones are either discontinued or were a special design specifically for Catalina. A prop of a given pitch but higher E.A.R. will get more thrust and thus act as if it has higher pitch.

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Main Message Board / Online prop sizing calculators

« on: April 17, 2019, 07:43:52 PM »

For reasons mentioned elsewhere here, I need to buy a new prop right now, a year earlier than planned. I had hoped to do some full throttle testing on my old prop this season, but that's no longer possible, so I have to go with the data I have available. If I can get some confidence in the specs, I may go with Flexofold instead of fixed prop. I know this has been discussed widely here, and we have somewhat different motors and transmissions. For this thread I'd like to focus on modeling results.

I spoke to one prop shop who took a few numbers from me and suggested I go with 15" x 10" 3-blade. I also spoke to CatalinaDirect and they took a much more extensive range of data and will get back to me tomorrow with their results.

I did find a couple of online calculators that gave me results ranging from 17" x 11" (Michigan Wheel calculator at https://www.miwheel.com/inboard-propellers/prop-it-now/ ) to 15" x 9" (https://www.vicprop.com/displacement_size.php). That's a huge range that just increases my confusion. I am curious whether any of you have any experience with these calculators and how they match up with your own experience.

Also, I found this article that warns of the dangers of over-propping, and makes me tempted to "leave well enough alone" with my current pitch: http://www.oceannavigator.com/January-February-2017/Are-you-over-propped/

FWIW, 15" x 9" 3-blade Michigan Sailer is what I currently have, and was thinking I'm a little under-pitched based on my max RPM of around 3400. But as I study this, I learned that there's more to this than just pitch, and things like E.A.R. can have an effect. My original Sailer design has very low E.A.R. (skinny blades) and is now discontinued and replaced by more skewed models that have significantly higher E.A.R. that could deliver more thrust (and more sailing drag) at the same pitch. That just complicates things more.

I'm open to your comments on the two models linked above, and any other online calculators that you're aware of. Many of them seem to be for powerboats, so one must select carefully.

11

Main Message Board / Re: Transmission replacement

« on: April 16, 2019, 07:11:36 PM »

PM on the way.

I also sent my boatyard a link to the CatalinaDirect website, and mentioned the downloadable instructions that are contained there. I'll forward any other info that you have as well. Thanks!

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Main Message Board / Re: Transmission replacement

« on: April 16, 2019, 06:59:38 PM »

Thanks for posting these pics! Your timing is perfect. I sent a link to my boatyard to see an example of how it's done with the Catalina strut.

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Main Message Board / Urgent: Sourcing a new strut

« on: April 16, 2019, 06:05:11 PM »

Hi all,

My boat needs a new prop, shaft, and strut. I think I have good leads on the first two, but the strut is a concern. The boatyard's supplier is planning to source it from Buck Algonquin. I believe that CatalinaDirect has the exact part, with the perfect (square) hole locations and perfect curve of the mounting plate, making for the best possible fit (and least man-hours of work). I know nothing about Buck Algonquin except some online pictures that show "generic" struts with no holes and a flat mounting plate. However, I realize it's also possible that Buck Algonquin might have an identical one to the Catalina/CatalinaDirect, and might even make it for them.

Do any of you guys know about Buck Algonquin as a replacement strut for our boats?

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Main Message Board / Re: Slipping transmission?

« on: April 15, 2019, 07:52:31 PM »

Hurth 50  2:1

Thanks, I'm rereading a lot of the stuff there which I had seen before, but it was less urgent at the time, so I had forgotten some of it. I had planned to spend this season with my refurbished 15"x9", do more extensive testing of motor RPMs with my strobe, check shaft RPMs vs. spec gear ratio to ensure there was no slipping, then make a decision on re-pitching. Now I'll almost certainly have to buy a new prop without that benefit. Almost makes me default back to another Michigan Sailer prop rather and save my $2100 for a future Flexofold after I have my data.

Sorry if my questions were repetitious - I need to go back and re-read a bunch of stuff before asking any more questions.

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Main Message Board / Re: Slipping transmission?

« on: April 15, 2019, 07:35:30 PM »

Thanks for the reminder. I'll go back and look at it again.

I remember that you had 15"x10" prop on a smaller motor, but Ray at Atlantis reminded me that the transmission gear ratio has a big impact, and could negate the larger motor. What is the gear ratio of your transmission. My Hurth HBW100 is 1.79 in forward.

I was planning to test full throttle RPMs on that trip as soon as I got into close range of my final destination. Unfortunately I did not make it far enough to run the test, and now I'll likely have to choose a new prop without that data.

By the way, I had put an anode onto my strut before launching. We'll see what kind of condition the strut is in soon.