types of inboard shaft drive boats

Discussion in 'Boat Design' started by larry sellers, Sep 28, 2012.

  1. larry sellers
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    larry sellers Junior Member

    Hello, First post, new member. Although I have had several boats, power and sail, I'm ignorant and out of date. More of a river-guy (Sacramento delta live-aboard (sail and power) for 15 years, long ago).

    So I have questions...

    I'm considering what I might want for the Coos Bay Oregon area, fair weather fishing, not very far offshore and I have in mind the equivalent of a Chris-Craft 251, except I believe these as-built with 305 or 350 engine are over-powered for my intended use and also for the desired fuel consumption. (I want to avoid out-drives, except possibly a ford-volvo set-up.)

    In my ignorance I expect a Chris 251 re-powered with an "iron duke" 4 cylinder engine might be just the ticket.

    So, questions:

    What boats are approximate equivalents?

    Is the mooted engine swap a "will-fit" bolt-up to the velvet drive?

    Naturally there are many more question, but one must begin with a first step...

    Any remarks anybody cares to make will be welcome...

    Best!
     
  2. eyschulman
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    eyschulman Senior Member

    Will you have to run an inlet with possible breakers? If so you may have to make sure your boat can handle that. I do not know Coos Bay but many West coast areas have challenging access.
     
  3. larry sellers
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    larry sellers Junior Member

    Thanks for the reply! Indeed they do! My time in the Delta occasioned numerous unintended groundings, particularly when under sail. And it's something to consider, as nearby ports to Coos Bay have bay barrier bars that are dangerous. However Coos Bay is considered to be an international harbor, with MLW channel depth of 37 feet (claimed). Anyway it's plenty of water for small boats. see http://www.portofcoosbay.com/channel.htm Again, thanks for the response. Best!
     
  4. larry sellers
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    larry sellers Junior Member

  5. PAR
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    PAR Yacht Designer/Builder

    A 305 Chevy on a Velvet Drive will have in the neighborhood of 200 HP and weighs about 900 pounds. A 350 will be in the same range, with potential for more HP at the same weight. A 181 GM L4 (Iron Duke) will have 120 HP and I've seen them with 180, but I've always questioned if this was particularly accurate or a marketing ploy. You will save a couple hundred pounds, but with half the output.

    Considering the hull volume of the Chris-Craft 251 Catalina hull, you're going to need all the torque the small block can offer, to drive it into contrary currents, cross winds and bucking a head sea.
     
  6. larry sellers
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    larry sellers Junior Member

    Many thanks. The matter of wind-loads was on my mind. The power levels you state are higher than my estimates were, but in the park, so to speak. And the Chris is a heavy boat, they say, at about 6k (+) lbs. (My estimate was 100 hp for the L4.) I'm not committed to the Chris, it's mooted simply as a general type. And I'm not entirely opposed to the V8 either. In the long past I have built some 350's that were rather thrifty. I'd prefer a ford, frankly, as they seem (in my 20 years ago experience) to hold up better in marine usage. I favor the 260 and 289 fords that Crusader used to market in Whitcrafts (mated to eaton drives) in the early 60's - back when the rocks were still smoking. The horrible fact is that I don't know what engine will mate to what inboard transmission. And I don't know what other boats, other than the Chris 251, are approximately similar in that they are gas with shaft drives, deep V, about 25 feet. I sold, years back, a Steelcraft with a single flathead - wish I had it now...pretty boat.
     
  7. PAR
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    PAR Yacht Designer/Builder

    It's okay to be old Larry. The newer engines are much better in most regards then the old 289's and 283's etc. left over from the 50's and early 60's. You especially don't want a flathead in spite of the coolness, it has lousy power to weight potential.

    You'd be hard pressed to get a 100 HP L4 to drive that boat up on plane, though once up on plane a 100 HP Iron Duke would make 18 to 20 MPH in flat water. The problem is the torque to drive her "over the hump" which I don't think you'd have with 100 - 120 HP on that hull. 120 HP just might get it done in flat water, but any chop might slap you off plane. I'd thing 150 would be the minimum to offer enough reserve to keep you up and scooting. It's possible to get 150 from an Iron Duke, but a bigger straight 6 would serve you better. The straight 6's have much better torque, while still being economical and simple pieces to live with.

    Another option is the Mercruiser 3.7 (GM L4) 224 CID, which is available as 170 - 190 HP and the crate engine long block is less then $2,400 bucks at full retail.

    The Indmar 3.0 (Iron Duke) 181 CID is available at 140 HP, for less the $2,100 full retail. This is a complete engine, with covers, pumps, full electronic ignition, but no carb (I think).
     

  8. larry sellers
    Joined: Sep 2012
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    larry sellers Junior Member

    Thanks! I have worked on, serviced, GM 4 cylinder engines (mated to mercruiser drives) that were said to be "1/2 of a 454", I suppose that's the 224 cid engine you mention...they had presto-lite (ford) distributors (!)(?). Anyway they were potent as twins on the Sacramento river - pretty flat water, usually. And I have seen 292 in-line GM 6 cylinder engines mated to inboard transmissions in a houseboat, really a barge with a house. They seemed nice, narrow, fitted snug into the hull, but not easy to get to, as the living space was up against the machinery without any access except by crawling up along the shaft space. Since that hull was rusted out and leaking badly it was perhaps a bit dangerous too. I was afraid that I'd punch out the rust with my hand...

    Yeah, flatheads are pretty, but, as you say, heavy and their low compression makes 'em thirsty for the power they make. I used to see Chrysler inline flathead 8's now and then...

    But to reply on theme - I take it that, using the C.C. 251 as a model, the 350 engine is a pretty fair compromise, ie they did a good job. And I'd do well to stay with that engine, thus making the question of what will bolt up sort of silly. Still, is the flange and so forth the same on the 4 cylinders as it is on the 350? Would either of the 4 cylinder GM engines or a 6, say a GM 235 or 292, fit up? (Naturally the fwd mounts and auxiliary components are another matter) I doubt that I would often put the boat I'm going to find on plane, just motor out a few miles to fish - but when full power is needed... I understand that. Stuff happens.

    In the boats I have worked on years ago the stringers, the longitudinal elements under the engine mounts were glass-over-wood with lag screws through into the wood. These were almost invariably rotten - these were river-used boats of venerable age. Is the C.C. 251 similarly constructed, ie wooden stringers glassed over? Are rotten stringers a probable? (Same for transoms??)

    And many of the boats with V8's that I used to work on (on the river) were "turned 'round" 327's (and etc) such that the flywheel end was forward and the drive was taken off the timing-chain end using somewhat exotic castings. Is that still something one sees often, ie in newer boats?

    And what other production boats of similar configuration are fairly common?

    Again, many thanks for the kindness y'all are showing. I'm out of date and simply ignorant. (I can overhaul an old Eaton model B drive or a dana drive - but that's a worthless skill.)
     
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