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Author Topic: Repowering advise  (Read 1243 times)

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jcallis

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Repowering advise
« on: January 21, 2017, 09:56:24 AM »

Has anyone re-powered their Catalina 34 with a Beta 25 or a Beta 30 that can help me decide which would be the best application for my boat?

I have a 16 inch 3 blade max prop and am considering the Beta 25 or Beta 30 each with a 2.5:1 reduction gear.
 
I am interested in hearing about the prop size that you have used, and at what RPM you are able to hit hull speed at.  Also the cruising RPM that you find best and the boat speed at that RPM.  Additionally, does anyone have any experience with the Beta Marine 25 having too little power or the Beta Marine 30 having too much?

I know it may sound odd that the  Beta Marine 30 may have too much power, but the Beta Marine will swing a larger pitched prop, and could hit hull speed too soon, and not allow the engine to reach  its full  rated RPM.

I donít actually own a Catalina 34, but I have found your forum to be very helpful, and my Sabre 34 MKII has very similar characteristics.  The displacement and water line are almost the same (11900 lbs. displacement and 28.25Ē water line length)

Thank you so much for your help in advance
John
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Stu Jackson

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Re: Repowering advise
« Reply #1 on: January 21, 2017, 10:23:54 AM »

John,

Welcome.

Have you tried a search on Beta?  I just did and there are two pages with 38 hits, many of them discuss repower with different sized Beta engines.
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Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  Cowichan Bay, BC  Maple Bay Marina  SR/FK, M25, Rocna 10 (22#) (NZ model)

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jcallis

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Re: Repowering advise
« Reply #2 on: January 22, 2017, 06:05:27 AM »

Stu

Thanks for your reply.  I have read everything that I can find, but I suspect  I may have  missed some old posts.

I  have been  particularly impressed by the work done on black dragon with regards to the Beta 25 installation, and I know that Andrew Harvey was going to install a Beta 30 in his.

I am at the point were I know that I  am re-powering with a Beta Marine 25 or 30, and am trying to figure out if one will be better than the other.

I was unable to  find any details about the performance that Steve and Andrew" experienced with their re-power projects.  And it would be helpful to know what kind of prop size and pitch they were able to swing and the kind of  speed they  were getting.

Thank
John
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Stu Jackson

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Re: Repowering advise
« Reply #3 on: January 22, 2017, 07:53:06 AM »

John,

Understood, and I hope you find the other links from a search.  I just re-read Steve's account, and there was no mention of him changing his prop.  I don't recall if he did before he left years earlier for Mexico.  FYI, he and his family sailed from Vancouver to Mexico, then trucked the boat back.

Re: 25 or 30; assuming that's the HP, I have been running our M25 21 hp for the past 18 years, and last summer motored all the way up the Pacific Northwest coast from SF to Vancouver Island.  Now have 3244 engine hours.  I have a "standard" 15x10 fixed 3 blade, and ran at 2650 to 2800 rpm for days on end, hours on end, at 6 to 6.5 knots.  We experienced both headseas and following seas and I use our knotmeter and GPS to let me know the difference, having sailed in tidal waters almost all my life.  I don't think you can do much more than that on a 34 foot hull without expending more energy to making the stern squat even deeper and using more fuel per hour.   We used 0.6 gph on our trip, while I had been getting 0.5 gph for the previous 18 years, attributed to the higher rpm coming up the coast.  We also have a 100A externally regulated alternator.  Back in SF my friends with M35 30 hp in Mark IIs could slowly pull away from me, but I didn't run at 2800 to try to keep up; I guess they could eek out maybe a 1/4 knot more cruising.  Summary: ya can't go any (much) faster but ya can use more fuel!  :D

Black Dragon was recently sold by Steve aka waterdog.  You can pm Steve, who still checks in here (and the software sends emails).  He'll be glad to discuss it with you.  I forget who the new owner is, but he may see this and contribute, too.  pm Andrew, too, it's a great vehicle for getting in touch, although I continue to recommend that it be used for contact and that the "meat" of the discussions be shared with the group, for example: just your situation here, and for future references.

Good luck.
« Last Edit: January 23, 2017, 12:16:05 PM by Stu Jackson »
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Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  Cowichan Bay, BC  Maple Bay Marina  SR/FK, M25, Rocna 10 (22#) (NZ model)

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kwaltersmi

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Re: Repowering advise
« Reply #4 on: January 24, 2017, 09:37:58 AM »

I can't speak to the specs, proper operating rpm's, etc. of the Betas in question, but I can say that my C34 with a Universal M25XPB sometimes feels underpowered. I've seen the M25XPB's shaft hp rating listed anywhere from 21 - 26hp. I don't think the C34 (and likely your Sabre) would be overpowered with 30hp, as evidenced by the MkII's with the 30hp M35.
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Stu Jackson

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Re: Repowering advise
« Reply #5 on: January 24, 2017, 10:41:38 AM »

.............................. I don't think the C34 (and likely your Sabre) would be overpowered with 30hp, as evidenced by the MkII's with the 30hp M35.

An alternate approach to this reasoning is this:  As I reported earlier, my 21 hp does just fine on my boat at 0.5 to 0.6 gph.  My friends with M35 engines don't go much faster than I do, but they burn at 1.0 gph.  For what benefit?

It could well be that a "mid-sized" 25 hp engine replacement would make good sense.
« Last Edit: January 24, 2017, 10:53:56 AM by Stu Jackson »
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Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  Cowichan Bay, BC  Maple Bay Marina  SR/FK, M25, Rocna 10 (22#) (NZ model)

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waterdog

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Re: Repowering advise
« Reply #6 on: January 26, 2017, 01:47:27 PM »

My head is in a couple of Volvos and a small Kubota on my genset so the mindspace reserved for the Beta has been purged!   In any case I did the repower with the same fixed 3 blade prop I always had.   I don't recall prop size / pitch but it was standard issued Catalina 34.     Likewise I don't recall RPMs achieved but my recollection was it was a perfect replacement for the M25XP it replaced.   There was no need to do anything with the prop.   I was quite happy with the 25 at the time and distinctly recall being glad I didn't go to the 30.   Though I imagine if I had squeezed the 30 in, it likely would not have been too much power. 
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Steve Dolling
Former 1988 #804, BlackDragon - Vancouver BC
Now 1999 Manta 40 cat
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