I posted in the other thread praising my A4 but I did mention it was a financial decision, used diesels commanding an unreasonable (IMO) premium over the A4. An old motor is an old motor...
That being said, I would prefer to have a shiny new diesel any day. I looked into the beta marine 20hp A4 replacement and it's an appealing option. I'm not likely to re-power my 32 however as we're seriously considering a departure from the rat race... and a new (old) boat. On the topic of motoring into strong wind and waves .. we were off of Kingston this summer motoring back west into a 20 to 25 knot headwind and big square Lake Ontario chop .. 4 to 5 knots with the A4. I put the main up with two reefs and picked up another half a knot or more, not so much for powering the boat as balancing it for a smoother ride. Suhana did well that day. Steve Suhana, C&C 32 Toronto On Wed, Jan 29, 2014 at 8:37 PM, Peter Fell <prf...@gmail.com> wrote: > Keep in mind that a lot of the C&C's supposedly came with the > 'Stevador' version of the A4, which had a restrictor plate in the intake > manifold. My C&C 27 owner's manual (1980 version) lists them used up to the > C&C 36. Horsepower on these 'Canadian' market A4's was limited to 15hp. > > I think you only get RPM's up in the 3000 range with the 2:1 drive on the > A4, which again same source lists as being used on the C&C 34 and 36. > 2-bladed props for those listed at 16x10. > > The spec, and general rule of thumb that I understand is that the A4 has > to get up to 1800 rpm at hull speed. I've read a lot of posts on Moyer's > site, etc. where owners report maxing out at 2000 or so. > > The Indigo prop is a 3-blade 10-inch by 7.7-inch pitch bronze prop that > maker claims gets WOT up to about 2400 rpm, with cruise in the 1900 range. > The CDI 'perfect pitch' 2-blade 12 x 7 plastic propeller is the one that > flexes down to about 12 x 6 with load .. Dennis you might have been > thinking of that one. > > Now that all being said my '79 C&C 27 did not have the restrictor plate > ... and is 1:1 and still has the original 11x7 2-blade fixed prop. I don't > have a tach (yet) so I can't give you any data. > > Personally I'm contemplating a Flex-o-fold for mine ... they recommend a > 12x7 2-blade at $1030 (US) including shipping. Maybe the Indigo ($350). > But probably not this year though ... I'll put a tach in a and gather some > baseline data 1st. > > ANYWAY .... to the OP - keep your eye out. I obtained an entire A4 > freshwater cooled parts engine for the cost of a good bottle of scotch and > a bottle of gin! > > > > *From:* Dennis C. <capt...@yahoo.com> > *Sent:* Wednesday, January 29, 2014 4:37 PM > *To:* Cn Clist <CnC-List@cnc-list.com> > *Subject:* Stus-List The real reason to switch from an AT4 to a diesel > > Explosivity of gasoline? - No > Increased fuel economy? - Maybe > Torque/horsepower? - Yes > > The AT4 is rated at 28-30 hp at nearly 3000 rpm. The AT4 torque/hp curve > is fairly steep. That is, at 1400 rpm, the AT4 is only generating 12 hp or > so. At 2400 rpm, it's about 20 hp. Torque follows hp closely. > > Most marine AT4's have a 1:1 tranny. That means, in order to generate 30 > hp, the prop is spinning at 3000 rpm. That's why AT4 props are usually > pitched around 6. Exclusive of the Indogo prop which has a somewhat > flexible pitch, at 3000 rpm in heavy seas, most likely, the prop will be > cavitating and not efficiently transferring the horsepower to the water. > > On the other hand, diesel torque curves are fairly flat. A Universal > 25XPB reaches max torque at 2000 rpm. With a 2:1 reduction tranny, the > prop is only spinning 1000 rpm. Diesel props are pitched around 14-15. > You get a lot more bite with a higher pitch prop. > > In practical terms, imagine you are punching into 2-4 foot seas. With an > AT4, you might make 2-3 knots and a LOT of bubbles. (Been there, done > that. Touche' had an AT4 when I bought it.) With a diesel, you might be > making 4-5 knots. BIG difference. > > Let me relate another experience. One day we were struggling against > 20-25 knots and 1-2 foot seas in Touche' (35-1) with the AT4. We were > making 2-3 knots. My friend came by us in his 35-1. He was making 5-6 > knots. His 35-1 had a Universal 25 XPB with a 14 x 14 2 blade folding > Martec prop. Even with the folding prop, he was waaay faster than us. > > After I repowered Touche' I had to motor off a lee shore in a tropical > storm. 45 knots and 2-3 foot seas. I cringe at the thought of having to > do that with an AT4. > > Before the repower, I had to carry extra fuel or stop halfway to refuel on > my way to Pensacola from Lake Pontchartrain. Now I can make it all the way > motoring if I don't run hard. > > Please don't take me wrong. I like the AT4. I respect the AT4. I've > owned 2 of them. I think it's a great engine for motoring in and out of a > harbor. I don't think it's a great engine for certain white knuckle > situations or for motoring long distances. > > Dennis C. > Touche' 35-1 #83 > Mandeville, LA > > ------------------------------ > _______________________________________________ > This List is provided by the C&C Photo Album > http://www.cncphotoalbum.com > CnC-List@cnc-list.com > > > _______________________________________________ > This List is provided by the C&C Photo Album > http://www.cncphotoalbum.com > CnC-List@cnc-list.com > >
_______________________________________________ This List is provided by the C&C Photo Album http://www.cncphotoalbum.com CnC-List@cnc-list.com
