A4 in 38 footer

[jtsails]

New guy here, shopping for a boat to get back into sailing after a long absence. One of the boats that I am considering is a 38 footer that still has the original A4 with a 2:1 reduction gear. I'm not finding much info about this combination and am curious as to what performance I can expect. I will be using the boat as a weekend cruiser with an occasional race thrown in.
thanks
James

[Marian Claire]

jt: Welcome to the forum. I have the 2 to 1 reduction gear. After a meeting with a fellow forum member, Hanley whom also has the 2 to 1, I started checking on improving my boats performance by changing props etc. The bottom line is the A-4 was not designed to push heavy boats for long distances at hull speed. Displacement, prop size and pitch, prop in an aperture all effect performance. The 2 to 1 allows the A-4 to run at higher rpms and therefor have higher horsepower. 2000 rpm = 15 hp 2500 rpm = 20 hp 3000 rpm = 25 hp according to the A-4 info.
The MC displaces 10,000 lbs+ and I was told it would require something like 20 hp to get her to hull speed 6.7 knots.
If all you are using it for is short trips and not fighting strong winds or current you should be fine. I have covered thousands of miles in all kinds of conditions with my A-4. Often the progress was slow but she has always gotten me home.
Dan S/V Marian Claire

[Dave Neptune]

How big

James, first welcome to the forum!
I have an old 35 footer with a relatively short water line of 25 feet. I displace around 14500 lbs and tow a 10' lap strake rowing dinghy. I have a direct drive and am very pleased with the performance that the Indigo prop has given to me. Yes I would like to have a bit more power however I can cruise at 6.2kts @ 2200 RPM when the bottom is clean motoring to Catalina. I can push harder but just don't since my engine IS 43 years old and still ticking away albeit a bit on the tired side to say the least . With the 2:1 unit depending on the hull configuration you would be fine just not fast and how much is that extra knot worth. There are many mor prop options with the 2:1 unit which is a plus . The A-4's are simple reliable and very quiet all plusses.
Perhaps Russ will chime in he is 36' with the reduction unit.

Dvae Neptune

[jtsails]

thanks for the replies guys. My cruising area doesn't have tides so that won't be a concern and the only extended motoring will probably be in protected areas of the ICW or in calm weather (if it is blowing, I'll be sailing!!). The specs on the boat in question are 14700 displacement and 29'7" waterline. I'm not interested in winning drag races while motoring and will be happy with 6+ knots and 1 gph consumption. I realize that a lot will depend on the condition of engine and I'll be giving it a good hard look. BTW, Dan, when I do find a boat to buy I plan to keep it in the Oriental area, so I'm sure that we'll have the opportunity to meet.
James

[Marian Claire]

I look forward to it. The Neuse/Pamlico area is hard to beat for sailing options. Dan S/V Marian Claire

[msauntry]

With the right prop you shouldn't have any problems. I'm 35 ft/13K lbs. with direct drive and Indigo prop. I can hit 6.2 kts. Any more boat should have the reduction drive so you should be fine. Who knows what prop the previous owner threw on there, though.

[lat 64]

I'm a 2:1 also.
A 36-footer at 12,000 lbs. Works great!
I have asked Santa for Dave Gerr's "The Propellor Handbook" for Chrisrmas. After the new year I shal be all up and annoying with data about prop size. The bottom line is just that you plug in all the factors and get a closer idea about good prop size. doesn't need to be a guessing game.

Cheers,
Russ

[dvd]

I'm a 30 footer at 10,500 ilbs + with 2 to 1 reduction gear and at cruising speeds I have always had plenty of power. Getting to idle properly, thats a whole different story.

dvd

[edwardc]

I have a 32 footer @ 12,800 lbs, with a 2:1 v-drive and a 3-blade 15R8 prop.

In flat calm, it does 6 kts at 2400 rpm, almost 7 at 3100 rpm (wide open throttle).

With an 18-20 kt wind on the nose and 3 - 4 ft waves, it averaged about 4 1/2 kts at 2800 rpm.

I could probably use another inch of pitch on the prop.

With that big 15" prop, the prop walk to port in reverse is pretty severe.

[ndutton]

If memory serves (and that's a big IF), I think we were swinging a 16x11 prop on the Islander 36, A-4 w/ reduction.

[jtsails]

Ed and Neil,
Thanks for the replies, that's the kind of info I was looking for! Ed, do you have any problems with overheating when running it at 2800 rpms? I'm not sure what prop is on the boat I'm going to look at, but given the history of the boat I'll be surprised if it is anything other than a Martec folding. Really looking for to my boat shopping trip this coming weekend!!!!
James

[edwardc]

... Ed, do you have any problems with overheating when running it at 2800 rpms? ...

The engine is a fresh rebuild and a brand new FWC, with now just 70 hrs on it. All summer long, at anything above idle, it would quickly go to 180 degrees and stay there, rock steady. Even at 2800 rpm into a headwind for two hours.

[Laker]

JT , Tell us what boat you are looking at ...

[jtsails]

I'm actually looking at quite a few boats, but the one in question is a mid 70's C&C.
JT

[Laker]

A good friend has a C&C 36 Redwing , good race record and thousands of cruising miles under the keel , original A4 humming along. No rebuild.

C&C is a fine boat.