Going diesel ?

There has been a lot of discussion about diesel versus gas, and the consensus here in the US seems to be "gas is best" unless you are on a commercial sport fishing rig that runs a lot. Diesel takes maintenance too, gas gives good power and is easily repaired, in relative terms. David Pascoe has written some nice pieces about it (notable marine surveyor). I don't think the additional cost of diesel can be financially justified in most of the cases, but financial justification is not always something people really care about. Sometimes "because I want to" makes all the justification needed.


Sometimes the words get in the way of the meaning, as I have some prop evaluation programs here at the house that use the terms you mentioned in a different way.

A slow planing hull could well be on a cruiser of 47 feet or so, with the large boat still able to get onto a plane but probably more happy at displacement speeds. The faster the planing hull, the more the bottom will look like a sheet of plywood, as the flat bottom drag boats are about as fast as it's going to get on the water.

Planing hulls get slower as the V section gets deeper. The more friction via wetted surface, the slower the hull or the more power it takes to equal a hull with a flat profile.

A perfect example is just about all the wood speedboats Chris Craft ever built. With few exceptions, they all had a flat bottom at the transom. As a result many of them inclucing my two 17' Sportsman models are fast for their power, great on smooth water, but very inadequate in the chop. This is where a boat like the 23' Lancer really comes into it's own, the Lancer or equivalent Commander hull will become the faster hull as the water gets rough.

Therefore just considering what you are getting ready to do (repower with diesel?) I am wondering how the terms are being factored into your motor selection and evaluation process. The 35 is a great boat, very good looking and with many good interior and performance benefits. They were offered with small block V8 power and also with big block 427 power. The smaller motor provided good power and speed, the larger motor made the boat really a muscle-boat in cruiser clothing, with what could be described as an "excess of reserve power".

In selecting diesel power, you should be looking for power no less than the characteristics of the small block gas V8, which should be readily available. Anything less will naturally reduce the cruising speed of the boat. As we saw during the recent thread on the Ship FANTOME, speed can be a safety factor, especially if you are on a body of water where rough conditions can blow up quickly.

If you really want to go overboard, install a pair of these turbocharged IVECOs like Warren did! They pushed his 38 along very nicely.


Hope the project goes well for you, send us some photos!

Regards,

Paul