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  OUTBOARD LENGTH ???

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Author Topic:   OUTBOARD LENGTH ???
JAC posted 08-07-2000 02:25 PM ET (US)   Profile for JAC   Send Email to JAC  
WITH JACK PLATES BEING THE RAGE ON MANY BOATS TO LIFT THE MOTOR AND IMPROVE PERFORMANCE,WHAT HAPPENS WITH USING A 20" OUTBOARD IN PLACE OF THE SPECIFIED 25" ? MY 18' OUTRAGE NEEDS NEW POWER AND I AM CONSIDERING THE OPTIONS. ANY RECOMMENDATIONS ? HAS ANYONE EXPERIANCED THE DIFFERENCE BETWEEN THE 4 CYL, 140HP vs THE 6 CLY 150 HP ? DOES THE POWER/ WEIGHT RATIO MAKE ANY DIFFERENCE ?
Clark Roberts posted 08-07-2000 06:14 PM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Jac, I have a 13' (20 inch transom) with an 8"set-back jack plate... engine is a 15" shaft.. great performance (accelleration and top speed... a little over 40mph with a 40 Mariner)... best thing is the shallow draft. It is possible that with the jack plate you can use the shorter shaft motor! I also have a jack plate (8" setback) on a 21 Revenge with a 135 Optimax Merc... raised about 5" and a 15' with a 40 Merc on a 5 inch set back jack plate.... up about 4 inches... The right set up is important, you need the correct prop and I use "Doel-fins" on all my engines .. helps keep a cap on the prop which is running very close to surface... I use the jack plates so that I can run in shallow water but the performance benefit is great also... Happy Whalin'.... The old man and the sea
lhg posted 08-10-2000 09:32 PM ET (US)     Profile for lhg    
I am using the setback/lifting plates on my twin engine Outrage 18 (one piece units by Springfield Marine, Cabela's catalog) and I like them very much, for any number of reasons. I would stay with the recommended shaft length (25"), however, for maximum flexiblity. That way you can still lift the engine up for surface piercing performance props, or run totally submerged "elephant ear" conventional props, which would slip at elevated transom heights.

Clark, if you are running your 135 Merc with the cavitation plate 5" above water, how do you avoid sucking air into the cooling system, with resultant engine damage? Five inches of lift is into the high performance realm, and most of those engines have specially modified water intakes, since the conventional ones would be half out of water at that height. Or is this not a problem?

Bill D posted 08-11-2000 07:18 AM ET (US)     Profile for Bill D  Send Email to Bill D     
Clark, I've been considering adding one of the hydraulic jack plates to my Conquest. I
used a fixed one on my Montauk and of course have used them on high perforamce bass boats. Question do you have any experience with the on a hull style like the Conquest? My thinking (however strange it is) is that with a Hydraulic I could on those rare calm days trim way out and up for max perforance, plus
get my 225 FICHT right at top RPM's which
OMC tells me is a good thing every now and then.I could then also lower into the water
to help keep it hooked up in rougher conditions. Right now trimmed out with a heavy load I'm 400-500 below max RPM, just fine at a light load. This is with a 19 pitch OMC 4 blade SS offshore prop. I also have a 17 pitch of the same prop that I swap to depending on load.
Anyway yours or anyone input would be appreciated. Of course if I went this route I would have to convince the Admiral that we really NEEDED this and it not just another toy for me to play with. She's getting wise to all my reason why I need to add something else to the boat. <grin>
Clark Roberts posted 08-11-2000 08:38 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Larry, the 135 is up between 4 and 5" and there is no problem with cooling! The water wells up at transom and the fin keeps water on prop and water intake... the doel=fin rides right at surface.. no prop blow out on hard accelleration either..only in a tight turn with lots of trim-out.. I think the fact that the old 21 hull has the recessed transom (notched in about a foot) provides some channeling of the water to benefit the set-up also! I'm using a 19" pitch Merc (std eqpt type) which a local prop guy modified (17" repitched to 19") .. not a good idea to mess with std props but I wanted to experiment and it works very well.. the trick in raising any engine is in the set-up!
It takes many tries to get it right and there are no real rules out there... I have discussed this with the Merc high performance people and some recommend using small hub props (blowing the exhause over the prop).... this for super high performance... go figure! The 13 with the 15" shaft 40hp Mariner is a real surprise.. no handling problems and speed that is unreal! it runs dead heat with 17 Whalers with 90hp.... All this is necessary for me because of the very shallow water around here! Happy Whalin' Clark

Clark Roberts posted 08-11-2000 08:41 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Bill, I have no experience with the Conquest hull but seems to me that a power jack plate is the way to go.. !!! I looked at one yesterday that is based on a "parrallelogram" linkage concept (moves engine out as it lifts it)... very interesting concept.... will get details for you if you like... happy Whalin'..... Clark
Clark Roberts posted 08-11-2000 08:48 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
PS> ask Big Z (Tom Zeno) about the shallow water on Spruce Creek! We took his 27 accross the flats at near low tide, like a rocket sled on rails!! How'd we do that, Tom? Not recommended for the faint of heart... but then, it wasn't my boat! heh,, heh... Clark...aka.. The Old Man and the Sea
Bill D posted 08-11-2000 10:37 AM ET (US)     Profile for Bill D  Send Email to Bill D     
Clark, sounds like a cool system. Yes I would like more info. Does it like its built to handle offshore conditions? Thanks.....
bigz posted 08-12-2000 03:23 PM ET (US)     Profile for bigz    
Heh heh yourself you old Mullet Snatcher ---

Yep just got her trimmed up on her wings and Clark "Kent" was doing the flying and I was doing the praying ---

Wobbly Knees Tom
lhg posted 08-13-2000 10:39 PM ET (US)     Profile for lhg    
About 10 years ago, Mercury came out with the first, (I believe) parallelogram jack/setback device, under their brand name and, obviously, painted black. Stiff price, about $1200 each. It worked the opposite of Clark's description, however, in that as you lifted the engine up, the parallelogram collapsed and the engine was closer to the transom. In the full down position, setback was about 12". I believe they're still available from Mercury, maybe the racing division.
Clark Roberts posted 08-18-2000 04:33 PM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Sorry for the delay on getting the parallelogram jack plate info but here 'tis>
Unit is by "T & H" Marine in Huntsville, Ala.
(267-772-0164). Power lift is via electro-mechanical (electric motor/screw jack) and gives lift up to 5" and set-back varies from 5-8". Unit is rated for up to 150hp and price is around $800 retail. You may want to call and get catalog and other info... I have a T & H manual jack plate on one of my Whalers and can say that quality is very, very high... Anyway, "that's my story and I'm sticking to it!!".... Happy Whalin'.. Clark... aka.. Old What's his Name?
bigz posted 08-19-2000 08:23 AM ET (US)     Profile for bigz    
Here is T&H Marine web site address if that might be of help --- http://www.thmarine.com

Tom

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