[Public-List] Prop Size Discussion

Michael dickdurk at gmail.com
Thu Mar 25 03:08:01 PDT 2021


It's nice to see an accurate description of what are really 
uncomfortable seas.
Michael Grosh
@220

------ Original Message ------
From: "Mike Meinhold via Public-List" <public-list at lists.alberg30.org>
To: "Alberg 30 Public List -- open to all" 
<public-list at lists.alberg30.org>
Cc: "Mike Meinhold" <meinhold272 at gmail.com>; "RICHARD HAZLEGROVE" 
<hazlegrove at aol.com>
Sent: 3/24/2021 6:45:23 PM
Subject: Re: [Public-List] Prop Size Discussion

>Richard
>   My beta 16 is installed with the TMC 40 gear at 2:1 ratio.  I still have
>the 13x7 2-blade prop. The engine tops out at about 3600 rpm, spins the
>prop at 1800. This is where my Atomic 4 drove the same prop and gave me 6.5
>knots calm water, clean bottom. Based on the power -rpm curve for the A4
>this was just about 16 hp, so I was pretty confident I could use the same
>prop.  It uses a lot less fuel than the Atomic 4.  I have been in 20 knots
>head seas with 3 foot waves - nasty  Chesapeake bay 30 foot long waves- and
>kept up 4.5 knots .
>
>I have neither heard or seen any evidence of cavitation .
>
>Regards
>Mike
>Rinn Duin 272
>On Wed, Mar 24, 2021 at 17:19 RICHARD HAZLEGROVE via Public-List <
>public-list at lists.alberg30.org> wrote:
>
>>  In the prop discussion from February I noted a comment from Mike on Rinn
>>  Duin 272 regarding his Beta 16 diesel conversion.  I am considering the
>>  same engine and would love to hear back from Mike with a few details such
>>  as his transmission reduction ratio, prop size and performance in clear
>>  water and in wind and chop.  I have heard great things about these engines
>>  and would like to learn of his experience in our Albergs.
>>
>>  By the way, I currently have a little BMW 12 hp diesel that has been good
>>  over the years but parts have gotten hard to come by.  It has a lot of
>>  torque and a 2.7 to 1 reduction gear spinning a 13”x14” three bladed prop.
>>  It will approach 6 kts with a clean wheel and bottom but less than half
>>  that in strong headwinds/chop.  The 13” prop may be a little tight in the
>>  aperture but I only hear/feel cavitation when running hard at full rpm’s
>>  into strong headwinds.
>>
>>  Richard Hazlegrove
>>  Quest 433
>>  Mobjack Bay, VA
>>
>>  > On Mar 24, 2021, at 4:05 PM, public-list-request at lists.alberg30.org
>>  wrote:
>>  >
>>  > Send Public-List mailing list submissions to
>>  >    public-list at lists.alberg30.org
>>  >
>>  > To subscribe or unsubscribe via the World Wide Web, visit
>>  >    http://lists.alberg30.org/listinfo.cgi/public-list-alberg30.org
>>  > or, via email, send a message with subject or body 'help' to
>>  >    public-list-request at lists.alberg30.org
>>  >
>>  > You can reach the person managing the list at
>>  >    public-list-owner at lists.alberg30.org
>>  >
>>  > When replying, please edit your Subject line so it is more specific
>>  > than "Re: Contents of Public-List digest..."
>>  >
>>  >
>>  > Please do NOT include the entire digest in your reply!
>>  > ======================================================
>>  >
>>  >
>>  >
>>  > Today's Topics:
>>  >
>>  >   1. Re: Prop Size (scott at scottmaury.com)
>>  >
>>  >
>>  > ----------------------------------------------------------------------
>>  >
>>  > Message: 1
>>  > Date: Wed, 24 Mar 2021 14:40:52 -0500
>>  > From: scott at scottmaury.com
>>  > To: Alberg 30 Public List -- open to all
>>  >    <public-list at lists.alberg30.org>
>>  > Subject: Re: [Public-List] Prop Size
>>  > Message-ID:
>>  >    <20210324144053.Horde.DkBOojFrjFIqlYi_ChxyXk9 at gator2001.hostgator.com
>>  >
>>  > Content-Type: text/plain; charset=utf-8; format=flowed; DelSp=Yes
>>  >
>>  > hey just a follow up, Michigan wheel has recommended that I get a 12"
>>  > / 11  three blade prop and that is what the engine guys have ordered
>>  > for the Bill of Rights
>>  >
>>  > Thank you all for your response, I'll follow up with this further
>>  > after some use this summer.
>>  >
>>  > Scott
>>  >
>>  >
>>  > Quoting John Johnston via Public-List <public-list at lists.alberg30.org>:
>>  >
>>  >> Regarding prop size- My Alberg 30 ( # 69) spent many more months at
>>  >> the slip this past year unattended than I had anticipated. Last
>>  >> October I came down to the Bay from my home in Massachusetts
>>  >> intending to spend a pleasant month sailing. It turned out that
>>  >> while the diesel fired right up, I had no forward or reverse motion.
>>  >> The shaft was turning, but no motion. I thought perhaps it was
>>  >> barnacles on the prop, and I hired a diver to give it a scrape and a
>>  >> scrub, but he resurfaced in a minute and informed me that I had no
>>  >> prop, just a hub. Severe galvanic corrosion. The story goes on, but
>>  >> the point is that I am looking to buy a new prop.
>>  >>       My diesel is a Westerbeke 20 2B. Not the original engine, but
>>  >> when a previous owner installed it they kept the 2 blade prop that
>>  >> was appropriate for the Atomic 4. I decided to upgrade to a three
>>  >> blade Chesapeake prop at that time,  (5 years ago) which was deemed
>>  >> to be the proper, well, prop, for the new engine and transmission.
>>  >>      However, now it is time for a new prop. What I had bought was
>>  >> a 13x12x3 from Miller Island. Lovely piece of work, but it is shot.
>>  >> I have also been doing some research and reading, and came across an
>>  >> article about prop size by Ted Brewer more than a decade ago, and he
>>  >> maintains that the prop in an aperture should never have less than
>>  >> two inches of clearance at the top of the blade, to avoid
>>  >> cavitation. The aperture height on my Alberg is 14?. To achieve that
>>  >> 2? would be a 10? prop, which seems awfully sleight. I am thinking
>>  >> perhaps an 11? prop with whatever adjustment to pitch would be
>>  >> appropriate. Or maybe 12? as a compromise.
>>  >>     I would very much welcome the wisdom of the elders, and
>>  >> everyone else that has expertise or experience  with this matter.
>>  >>     Thanks to anyone offering their experience or advice
>>  >>
>>  >>> On Feb 24, 2021, at 7:41 AM, Mike Meinhold via Public-List
>>  >>> <public-list at lists.alberg30.org> wrote:
>>  >>>
>>  >>> ?Scott
>>  >>> I am glad to hear Bill of Rights will be sailing again.
>>  >>>
>>  >>> If you have some specs on the Vetus 25 we can see how it compares with
>>  the
>>  >>> A4 -13x7 2-blade match that you most likely have
>>  >>>
>>  >>> I repowered with a beta 16 and kept the same prop as I found it was
>>  about
>>  >>> the same operating point
>>  >>> We would need the engine torque and power vs rpm, and the gear ratio to
>>  >>> check.
>>  >>>
>>  >>> For the sails I suggest you provide the sailmaker with  the Chesapeake
>>  >>> Alberg rules in the Association handbook.   I highly recommend 2 reefs
>>  and
>>  >>> use both frequently.
>>  >>>
>>  >>> Mike
>>  >>> Rinn Duin 272
>>  >>>> On Tue, Feb 23, 2021 at 21:26 Bill of Rights #487 via Public-List <
>>  >>>> public-list at lists.alberg30.org> wrote:
>>  >>>>
>>  >>>>
>>  >>>> Hello everyone, I am a long time A30 owner and also had a Tartan 34-2
>>  >>>> for 10 years, I just recently sold that boat.
>>  >>>>
>>  >>>> I'm putting all my efforts back into #487 "Bill of Rights" this year!
>>  Yea!
>>  >>>>
>>  >>>> I am re-powering to a 25HP Vetus engine with a 2:1 hearth gear and
>>  >>>> just wanted to hear what others have "sized" for a 2 blade sailor prop
>>  >>>> on other diesel conversions?
>>  >>>>
>>  >>>> The At-4 engine was rebuilt and has less than 10 hrs.   Any interested
>>  >>>> parties should reach out to me
>>  >>>>
>>  >>>> I'm also getting a new suit of sails from Precision, #400 series! Does
>>  >>>> anyone have any experience or suggestions would be helpful  Main w/ 2
>>  >>>> reefs,   135# headsail w luff  ??????????
>>  >>>>
>>  >>>> New interior cushions!
>>  >>>>
>>  >>>> Boat still has some deck issues and I'll have to fix that as I go
>>  >>>>
>>  >>>> Hope to catch up with like-minded a-30 sailors this summer on the bay.
>>  >>>> I am securing a slip on the Magothy River so I'll be closer to my home
>>  >>>> and sail some new waters this summer!
>>  >>>>
>>  >>>> Thanks   Scott
>>  >>>>
>>  >>>>
>>  >>>>
>>  >>>> _______________________________________________
>>  >>>> These businesses support your Association:
>>  >>>> http://www.alberg30.org/store/A30supporters.html
>>  >>>> Please support them.
>>  >>>> _______________________________________________
>>  >>>> Public-List mailing list
>>  >>>> Public-List at lists.alberg30.org
>>  >>>> http://lists.alberg30.org/listinfo.cgi/public-list-alberg30.org
>>  >>>>
>>  >>> _______________________________________________
>>  >>> These businesses support your Association:
>>  >>> http://www.alberg30.org/store/A30supporters.html
>>  >>> Please support them.
>>  >>> _______________________________________________
>>  >>> Public-List mailing list
>>  >>> Public-List at lists.alberg30.org
>>  >>> http://lists.alberg30.org/listinfo.cgi/public-list-alberg30.org
>>  >>
>>  >> _______________________________________________
>>  >> These businesses support your Association:
>>  >> http://www.alberg30.org/store/A30supporters.html
>>  >> Please support them.
>>  >> _______________________________________________
>>  >> Public-List mailing list
>>  >> Public-List at lists.alberg30.org
>>  >> http://lists.alberg30.org/listinfo.cgi/public-list-alberg30.org
>>  >
>>  >
>>  >
>>  >
>>  >
>>  > ------------------------------
>>  >
>>  > Subject: Digest Footer
>>  >
>>  > _______________________________________________
>>  > These businesses support your Association:
>>  > http://www.alberg30.org/store/A30supporters.html
>>  > Please support them.
>>  > _______________________________________________
>>  > Public-List mailing list
>>  > Public-List at lists.alberg30.org
>>  > http://lists.alberg30.org/listinfo.cgi/public-list-alberg30.org
>>  >
>>  >
>>  > ------------------------------
>>  >
>>  > End of Public-List Digest, Vol 4139, Issue 1
>>  > ********************************************
>>
>>  _______________________________________________
>>  These businesses support your Association:
>>http://www.alberg30.org/store/A30supporters.html
>>  Please support them.
>>  _______________________________________________
>>  Public-List mailing list
>>Public-List at lists.alberg30.org
>>http://lists.alberg30.org/listinfo.cgi/public-list-alberg30.org
>>
>_______________________________________________
>These businesses support your Association:
>http://www.alberg30.org/store/A30supporters.html
>Please support them.
>_______________________________________________
>Public-List mailing list
>Public-List at lists.alberg30.org
>http://lists.alberg30.org/listinfo.cgi/public-list-alberg30.org




More information about the Public-List mailing list