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20 hp Beta as Repower for 1982 C-30

Mikem

.
Dec 20, 2009
753
Hunter 466 Bremerton
Considering a Beta 20 hp diesel as a repower engine for my daughter's 1982 C-30. It currently has the original 5411, 2-1 reduction gear, 3000 rpm, and a Gori two blade folding prop, 13 x 9 rh. With a clean bottom and WOT and no wind or current it will hit 5.4 kts GPS. My question is will a Beta 20, 3600 rpm, 2-1 reduction gear and a 3 blade fixed 13 x 9 prop (recommended by both Beta and Catalina Direct) achieve hull speed of 6.7 kts? Thanks, Mike
 
Jan 25, 2011
2,223
S2 11.0A Anacortes, WA
When I repowered, I talked to Beta in NC. They were very helpful in the choice. I see you’re in Bremerton. Be sure to discuss currents and passes and power to negotiate such. I went with a 35 which is one size up from their recommendation and glad I did.
 

Mikem

.
Dec 20, 2009
753
Hunter 466 Bremerton
When I repowered, I talked to Beta in NC. They were very helpful in the choice. I see you’re in Bremerton. Be sure to discuss currents and passes and power to negotiate such. I went with a 35 which is one size up from their recommendation and glad I did.
Did you put a 35hp Beta in a Catalina 30?
 
Jan 25, 2011
2,223
S2 11.0A Anacortes, WA
No, I put a Beta 35 into an S2 36 with a new saildrive and J-prop. The old Volvo was 36 hp and that what is what I going off of. Beta said the 30 would work fine but then stated the 35 might be better for PNW. I’m glad I went that route.
 

Mikem

.
Dec 20, 2009
753
Hunter 466 Bremerton
No, I put a Beta 35 into an S2 36 with a new saildrive and J-prop. The old Volvo was 36 hp and that what is what I going off of. Beta said the 30 would work fine but then stated the 35 might be better for PNW. I’m glad I went that route.
Ok. For a second I thought you wanted to water ski behind the C-30 with a 35 hp diesel. How does your boat perform with the Beta, new saildrive and J prop?
 
Jan 25, 2011
2,223
S2 11.0A Anacortes, WA
Also, there are sites for prop sizing that you can plug the particulars in and get the result.
 
Feb 1, 2014
82
Watkins 27 North East, MD
I have a Beta20 (722D block) , 16 hp nominal, in a 1980 Watkins 27@8000#. MAX RPM listed is 2800, IIRC I have a 13x9" pitch three blade. Am over propped by about 1.5 inches as I can hardly get over 1800 at close to hull speed. It *does* make for interesting backing and such .
The newer repl.is a z block 25hp. IIRC
 
Jan 21, 2009
231
Catalina 30 Lake Perry, KS
I have a 1988 deep draft Catalina 30. I have the standard 2 blade prop with a Universal 25XP engine. I sail on a lake in Kansas which rarely has waves more than 2ft.. Fortunately we have nice wind. I have a Garmin GPS which indicates I rarely I rarely achieve 6knts speed over ground at full throttle. The engine is rated at about 23hp. In the past Catalina used smaller diesels which proved insufficient. I think the Beta 25 would be about right. The Beta 25 is used to replace the atomic4 which was the original engine on the older Catalina 30s.
 
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Likes: Bob S
Apr 8, 2010
1,620
Ericson Yachts Olson 34 28400 Portland OR
We replaced an aging Universal M25XP (23 hp) with a Betamarine 25. At 10600# displacement, it was perfect. The former engine drove the boat @ 7 kts, and so does the new engine. We do have more DWL than the Catalina, but it should be easily able to motor at 6.3 or so, IMHO.
While the Beta 20 might be adequate, the 25 would seem to be -IMHO- a slightly better choice. Note that the purchase price of the engine in a crate is not that much different between the two - same trans and same panel. Best to focus on the 'fit' and the total labor to install it properly.
 
Last edited:
Apr 8, 2010
1,620
Ericson Yachts Olson 34 28400 Portland OR
I just surfed over the Betamarine site and as of late December they have a new section discussing which engine is recommended for several production boats, and one is the Catalina 30.
If the link will paste OK, here it is: Catalina 30 Engine Replacement
 
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Likes: Mikem
Jan 25, 2011
2,223
S2 11.0A Anacortes, WA
I would still talk to Beta how they derived their data. The OP needs to state how he/she wants to operate the boat. If the boat just leaves and arrives at a marina or mooring under power, then good. If the boat is intended to cruise Puget Sound and waters north, then I would discuss with Beta the requirements for dealing with winds and currents. Beta tried to talk me into a 30 for my S2 36 and my old Volvo had 36 hp and did well with currents etc. Cruising the PNW waters, I'm glad I chose the Beta 35. Just FYI, I could have also had the the Beta 38 which is not much different. In fact, it is the exact same engine but the 35 is "defueled". The 38 redlines at 3600 rpm and the 35 redlines at 2800. The 35 is much quieter at lower rpms with a little bigger prop and if wanted, I can run it wot all day if needed. Just sayin...
 

Mikem

.
Dec 20, 2009
753
Hunter 466 Bremerton
I would still talk to Beta how they derived their data. The OP needs to state how he/she wants to operate the boat. If the boat just leaves and arrives at a marina or mooring under power, then good. If the boat is intended to cruise Puget Sound and waters north, then I would discuss with Beta the requirements for dealing with winds and currents. Beta tried to talk me into a 30 for my S2 36 and my old Volvo had 36 hp and did well with currents etc. Cruising the PNW waters, I'm glad I chose the Beta 35. Just FYI, I could have also had the the Beta 38 which is not much different. In fact, it is the exact same engine but the 35 is "defueled". The 38 redlines at 3600 rpm and the 35 redlines at 2800. The 35 is much quieter at lower rpms with a little bigger prop and if wanted, I can run it wot all day if needed. Just sayin...
Mark, when I spoke with the Pt Townsend Beta dealer he said they had done four C-30s. Three with the 20 hp version and one with the 25. He said the 25 was for an older couple that would power much more than sail. Also the 25 requires some settee modifications that the 20 does not. Apparently the folks with the 20 were very satisfied. From the C-30 yahoo group forum one respondent from San Diego with the 20 said he achieves the 6.7kt hull speed at 3100 of the rated 3600 rpm. When I checked with Gallery Marine of Seattle they recommended the M3-20B as the engine of choice...also a 20hp 3600 rpm engine. Gallery said they have done numerous repowers with the M3-20B.

As to how they derived their original data I have no idea but the empirical evidence seems to indicate the 20hp is sufficient. Since the C-30 is advertised as a 10,500lb boat, 5.25 ton displacement and the rule of thumb for a displacement hull is 4-5 hp/ton the 20hp seems ok. In my own boat, the H466, advertised at 26,000 lb (13 tons) displacement and a 75hp yanmar has a theoretical hull speed of 8.3 kts at WOT I can achieve 8.6 kts with my 3 blade 20 x 14 flexofold.

And finally, after penciling out the cost of "new" engine repower and doing it myself the cost is about $12k. So I may have to go with used/rebuilt if I do it all. Thanks, Mike
 
Mar 1, 2012
2,182
1961 Rhodes Meridian 25 Texas coast
can't speak to the Beta, but in my 35 foot trimaran, my 20hp Yanmar did a beautiful job and I assume still is doing it.