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Author Topic:   Jackplate report
Montauk posted 10-11-2002 11:11 AM ET (US)   Profile for Montauk   Send Email to Montauk  
I just installled a CMC power jackplate on my 1973 Montauk w/90hp yamaha and after test driving could not be happier!!! It was a real hassle to do on the older boat, had to plug transom holes and redrill for bracket and buy a 1 foot longer steering cable. I started out with a Bobs' Machine shop power lift but it requires mounting a power unit in the console and running hydraulic lines to it from the lift, they were gracious enought to refund my money which allowed me to go with the self contained CMC unit. I gained 500 RPM's and 3 mph with a 15 pitch prop(aluminum) without trimming the motor and running it at the highest setting on the plate. I believe I can go to the SS17" prop I have and get better performance. Next step is to install a water pressure gauge and test with th ss17 pitch prop.
smgrogue posted 10-11-2002 11:29 AM ET (US)     Profile for smgrogue  Send Email to smgrogue     
Montauk--I am curious. Since you had a chance to evaluate both units, how would you compare the design and build quality of the Bob's to the CMC unit? Obviously, the CMC is self-contained, but what I am driving at is how the two are actually put together. Seems to me that the CMC uses a different lifting design. Also, what was the wight difference between the CMC and Bob's (the part that actually goes on transom). I believe the CMC is about 40-45 lbs with the fulid and the pump back there on the transom; Bob's should be less, but maybe it's also not as stoutly built? How is your static trim with the new setup? Splash well drains above water level? Congrats on your new setup and thanks for sharing. Stephen
smgrogue posted 10-11-2002 11:41 AM ET (US)     Profile for smgrogue  Send Email to smgrogue     
By the way, did you look at the Detwiler jackplates? I have read that they are good and looked at their site, but don't have any first hand info about them.
Montauk posted 10-11-2002 12:49 PM ET (US)     Profile for Montauk  Send Email to Montauk     
Montauk--I am curious. Since you had a chance to evaluate both units, how would you compare the design and build quality of the Bob's to the CMC unit? Obviously, the CMC is self-contained, but what I am driving at is how the two are actually put together. Seems to me that the CMC uses a different lifting design. Also, what was the wight difference between the CMC and Bob's (the part that actually goes on transom). I believe the CMC is about 40-45 lbs with the fulid and the pump back there on the transom; Bob's should be less, but maybe it's also not as stoutly built? How is your static trim with the new setup? Splash well drains above water level? Congrats on your new setup and thanks for sharing. Stephen
Stephen,
It is unfair to compare the two because the Bob's Model I had was a light weight model(38lbs)for up to 115hp and the CMC is for up to 300hp(45lbs). The CMC is thicker Alum. and heavier built, however I feel it is over built for my application. I like the fact that the CMC uses bushings instead of slides that require greasing. I was not worried about the weight difference because I have a trolling motor and Group 27 battery mounted in the front. Also have a homemade 20 Gal baitwell in the back and 28 Gal gas tank under helm seat. Splash well drain is above the water and trim is just right still. Overall the CMC unit it is a better fit for the Montauk because it is self contained and sealed. Warranty is one year on both pump units. I feel both units are built well and would not heitate to use Bob's in a different application. I will report again when I try the SS17 pitch prop and pressure gauge. Did not look at the Detwiler unit. By the way the Yammie props are technically surface piercing props so are a decent match for this application.
lhg posted 10-11-2002 02:10 PM ET (US)     Profile for lhg    
Be sure you get some kind of a performance oriented prop for your setup, such as a Stilleto, Mich Wheel Rapture, Mercury (with Yamaha hub)Trophy/High Five or other. You will need something that can run surface piercing to avoid slip. A conventional "elephant ear" SS prop is not recommended, as it cannot take advantage of the hydraulic jackplate.
Bigshot posted 10-11-2002 02:40 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Ditto if you are piercing the surface. You also need a pressure guage if doing it as well. Just because the water pump indicator is "talking to a man about a horse"....does not mean you are getting enough cooling. Do not go above redline and try a bigger prop.
Bigshot posted 10-11-2002 02:42 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
true....Yamaha uses a "cleaver" type SS prop. Should be fine. Bob's makes a nice nosecone with low water pickup for the 90 Yammie as well.
Montauk posted 10-11-2002 02:56 PM ET (US)     Profile for Montauk  Send Email to Montauk     
In the process of installing a pressure gauge and bigger prop right now.
Seabrook posted 10-11-2002 03:21 PM ET (US)     Profile for Seabrook  Send Email to Seabrook     
Montauk, think we discussed the jack plate in an earlier thread. I knew you would love it. Anybody that has ever used a jack plate on a Montauk will never go without one in the future.

How shallow are you running now? Did you install some type of fin on the anticavitation plate? What is your RPM at WOT?

Not sure exactly how shallow I run but I know there are some flats we wade fish that are less than knee deep and I can run in that area with no problem at all. I have a Stingray fin on the back that I think helps keep the raised motor from cavitating. Also, I use a 21" pitch, 3 blade OMC stainless prop on my 1983 Montauk with a 1983 Johnson 115. At WOT and the motor raised and trimed some I run about 5500 RPMs which is perfect since that is the upper end of the RPM range. The boat also jumps on a plane so there is no problem there with the higher pitch prop (I think my old 115 is better than average...seems a lot stronger and runs perfect) I do not have a water pressure guage but I do have a temp guage on the motor and it does not run any warmer than normal when jacked up.

I am getting my 18' Outrage back from the shop next week and can't decide whether to take the jack plate off the Montauk for the Outrage....or leave it on and buy a new one. Either way, I will have a CMC lift on the Outrage.

Montauk posted 10-11-2002 04:17 PM ET (US)     Profile for Montauk  Send Email to Montauk     
Seabrook,
I only could run the boat for about ten minutes this morning as I am at work(selling boats), so do not know yet how shallow I can run, it planes nice, but have to be light on the throttle to keep from cavitating. I ran at 5500 rpm's without trimming so feel I can go up in prop size without problems, did not want to run it trimmed untill the pressure gauge is on. I really don't care for anticavitation plates so will try to get by without one. You are right, I love it!
Montauk posted 10-14-2002 03:59 PM ET (US)     Profile for Montauk  Send Email to Montauk     
Tested with the SS19 pitch and the water pressure gauge today. More torque steer and very touchy on the throttle, Retested with the 17 and liked the response better. I am not ready to commit the funds for a real surface piercing prop so will run the 17 pitch aluminum prop. In my first post I was confused on which prop I tested, turned out to be a 17, so went up to the SS19. Water conditions were whitecaps with 25 knot winds. Overall the jack plate has done what I hoped for and I can still raise the motor up about 3 holes on the jack. Another benefit of the jackplate is it makes the 1973 hull ride much nicer in rough water and that alone is worth it!
John W posted 10-14-2002 04:52 PM ET (US)     Profile for John W  Send Email to John W     
You may eventually want to try a 4 blade prop if you're not going the surface piercing (max speed) route. Many flats & bay boats here in FL use jackplates for shallow water running, and most use 4 blade SS props to prevent the prop from blowing out at high settings or in turns. A 4 blade will also give you less prop torque if that's an issue. It won't give you quite the top end that a 3 blade cleaver prop will, but you'll get better accelleration & better overall performance, and your top speed will still be better than it was without the jackplate.

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