Areneson on a 27ft Uniflite?

Well mine is a cat, I ran left and right props in both port or stbd because I could not find out the information as to which way they should be.

I know now,-- it is (looking at the boat from the back, left is left and right is right. Actually it made no difference either way (being a cat I suppose).

Its not just a case of swapping props ,--its changing cables on both stations.

There has been many discussions about fixed and trim able, and to be honest I don't know how you can maintain all those hydraulics when you leave it in the sea.

Sony Levi the famous surface drive guru used to have a cup of tea on my boat frequently before I knew who he was. He told me trim able was not necessary and if you need trim able you have the wrong prop or you need more air/ exhaust.

I heard of a 80 foot Pershing in Europe with Arnesons and the steering hydraulics failed , the two drives came together, one can only Imagine the consequences of that.

 

The drives are held in sync via a mechanical tie bar so there is no way they can come together .

 

got a 30ish hp diesel for a 27' uniflite express borgwarner direct drive. prop size?

wondering if this will even work lol??? its a 1962. we dont wana go fast we just want enough power to bear some seas and be safe. is this plausable!?

 

Displacement Operation

I ran the figures on the Boatdiesel site using 7000 lbs and a 23 ft waterline. The results show your could expect about 7 knots cruising and 8.5 top while using 22.5 hp at the prop.

With a cruising rpm of 1800 and a reduction of 1.6:1, the recommended prop was 16 dia, 12 pitch.

The weight, waterline, reduction ratio and prop diameter were guesses on my part. I'd be happy to re-run the calclaions for you if you have different data.

If you can be satisfied with the speed, you'd have a very economical boat to run. I have a friend running a 31 ft express with a Honda 50 hp 4 stroke, and he's tickled pink with the results. I like your solution better.

 

The problem may be that there will be very little reserve power. In a blow the boat will not have enough HP to maneuver safely.

 

How much is enough?

I realize I'm off topic here, but please excuse this transgression as I reply. I agree with gonzo, safety always has to a primay concern; however, at some point wind and sea state will overwhelm any vessel. With an 8 hp yanmar diesel in a 32 ft sailboat, I've been able to make 2-3 knots against a steady 45 knot wind and a 3-5 ft sea (sails down). Under similar conditions I've also been unable to maintain course in a 26 ft Nordic Tug with 3 cyl Volvo rated at about 36 hp. I noticed that antiqueuniflite is from British Columbia and I suspect his biggest issue will be tidal currents. The diplacment speeds he'll be able to attain will require patience and near slack water conditions while transiting high tidal flow areas. Depending on the design of the vessel and prop used, the "push" or "pull" you get from a propeller ranges from about 20 to 35 pounds per hp, (more with the big props tugs use) so his 30 hp diesel should give him a minimum of 600 pounds of static upmh. Is that enough, no, not for all conditions; however, I'd be comfortable taking his Uniflite out under most situations.