Put Down Deposit Today
- Thread starter WeekiTiki
- Start date
ssobol":fj2657u2 said:
Ans.: The jack plate moves the whole motor mount up and down to change shaft depth, thus when the regular motor trim is used to tilt back for shallow water drive, the base of the motor mount can be higher by the amount the jack plate can raise the motor above normal un-adjusted height on the transom. The propeller and skeg will be higher by this amount, whether tilted straight down or back in the shallow water drive position. The jack plate can raise the motor and lower it as much as 6 inches or more.
Some illustration:
https://www.youtube.com/watch?v=62DwTnrU6FE
Joe. :teeth :thup
Shallow water boats are the norm around here, where they run in 8 to 10" of water (yeah, inches). Some of the boats have jackplates, but it seems they often have a slight tunnel at the back of the hull. These are scooter-type hulls that also have no coaming (think: raft-like); keep 'em light.
Other than commercial boats or sport fishers (that have to stay in the channels to get out to the Gulf), any kind of cabin boat is a rarity here.
Two foot tidal swings are typical, and there are flats that show at low tide that these flat bottom boats blast over mid-tide or higher. Not for me, but I understand why jackplates are desirable... on some designs.
Other than commercial boats or sport fishers (that have to stay in the channels to get out to the Gulf), any kind of cabin boat is a rarity here.
Two foot tidal swings are typical, and there are flats that show at low tide that these flat bottom boats blast over mid-tide or higher. Not for me, but I understand why jackplates are desirable... on some designs.
Sea Wolf":15qh2sjb said:
By "how is this different" I meant how will the boat performance be different. I would expect that when operating in shallow water where the motor needs to be raised a prudent operator would be running the boat at slow speed. In a slow speed condition the thrust line will not make much difference to the boat ride or handling. I would think with the motor tilted up at slow speeds the boat handling will be the same. Also, I think that the amount of lift you can get out of the tilt mechanism may be more than a jack plate. You can tilt as far as you want whereas jack plate has a certain amount of travel (usually a few inches). Relying on just the tilt also is a less complex installation.
With the motor jacked-up vs tilted when traveling in the shallows
you can run at higher rpms without prop-blasting
...and if you still need to tilt the motor
it doesn't have to be at such a great angle to the water
Motor I originally bought this jack for was a 1984 Johnson 140
I had Bob of Bob's Machine Shop, the mfg of the jack also
install a low water pick-up and nose cone on my lower unit
On a 15 foot Action hull that combo would literally fly across the water
you can run at higher rpms without prop-blasting
...and if you still need to tilt the motor
it doesn't have to be at such a great angle to the water
Motor I originally bought this jack for was a 1984 Johnson 140
I had Bob of Bob's Machine Shop, the mfg of the jack also
install a low water pick-up and nose cone on my lower unit
On a 15 foot Action hull that combo would literally fly across the water
