Losses might be 5 or 10 percent, but I never heard of almost 2/3s! There is the prop issue and gearing though, that 30 HP is at 3600 RPM. The only A4s that can do that are in planing boats or have the 2:1 reduction gear. Absent the gear you are probably at 22-24 HP at best and many A4s came severely overpropped and can't get past maybe 1400 RPM. This is really nice on a calm day, you hit hullspeed just off idle, but any headwinds will about stop the boat.
Joe Della Barba Coquina C&C 35 MK I www.dellabarba.com From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Rick Brass via CnC-List Sent: Monday, August 24, 2020 3:53 PM To: cnc-list@cnc-list.com Cc: Rick Brass <rickbr...@earthlink.net> Subject: [EXTERNAL] Re: Stus-List 37+ Cruise Speed I believe the difference is between rated HP and shaft HP, which is generally lower after things like transmission loss, accessory loads, and friction. IIRC, an A4 was rated as 30HP, but the shaft HP was something like 17or 18. Which is why an2 cylinder Yanmar is a suitable replacement foe an A4. Rick Brass Washington, NC From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Joe Della Barba via CnC-List Sent: Monday, August 24, 2020 2:15 PM To: cnc-list@cnc-list.com<mailto:cnc-list@cnc-list.com> Cc: Joe Della Barba <j...@dellabarba.com<mailto:j...@dellabarba.com>> Subject: Re: Stus-List 37+ Cruise Speed What the heck is a 13hp Atomic 4? Mine is 30 HP. Joe Coquina On 8/24/2020 1:26 PM, Daniel A. Willis via CnC-List wrote: My 1973 30' Mk 1 had a 13hp atomic four but was re-engine 12 years ago with a 20 hp Universal. She stops on a dime and handles very well with all that power. I suspect some might simply have been re-powered over the years as our Santiago was. ________________________________
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