What's this adjustable motor mount called & purpose?

[guy48065]

Another installment in my series of "Dumb Noobie Questions"

My ancient '79 Crest has one of those moving motor mounts that raises & lowers with a long lever attached to the side of the contraption. What is this thing called? Is its main purpose to raise the outboard for running shallow water, or to trim for weight distribution?

[spurhunter]

Its called a jack plate, and for all the reason you mentioned. Handy to have on some boats, mostly for performance only really.

[guy48065]

I always thought it was just for shallow water until last weekend--when I finally got my boat in the water and took it for a spin around the lake. The mount was at its highest position and the cavitation plate was submerged an inch or 2. At one point I walked forward of the helm and heard the RPM & "gurgling" increase & realized the weight shift raised the prop. I sure didn't think my 180# would make any difference in the attitude of a 21' pontoon.
I dropped it one notch & all was good.

Heavy bugger. Should there be springs? I don't see my wife managing that lever.

[ToonGuy]

Sorry guys, but I doubt his 1979 Crest has a jack plate He's talking about the old school adjustable transom. It would allow you to run a short shaft motor on the first pontoons, and you could raise it up out of the water while docked. It looks very simillar to this kicker bracket, with a long arm so you can raise and lower it from the deck...

[guy48065]

Darn! Back to not knowing.
No pix of the back of my boat but I found one on Google that looks similar

[lakerunner]

A friend had a late model Crest 3 log and it had an adjustable transom. He had a 150 Opti on it and it hauled ass.

[curtiscapk]

Old School tilt and trim....

[wedge542]

never seen nothing like that but the kicker motor bracket ive seen.

[guy48065]

They seem to be pretty common here on old or low-buck boats. The high-zoot ones of course have electric or hydraulics that tilt, trim, troll and dispense margaritas.