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Caviataion Plate
Posted: August 29th, 2009, 10:17 am
by rocket
Anybody think something similar to this
http://www.stiffypushpoles.com/shawwing.htm
is superior to a Bob's cavitation plate? Bob's sure is a lot easier on the wallet.
Re: Caviataion Plate
Posted: August 29th, 2009, 11:56 am
by wevans
Re: Caviataion Plate
Posted: August 29th, 2009, 2:12 pm
by Reel Cowboy
dam at
Re: Caviataion Plate
Posted: August 29th, 2009, 3:43 pm
by Chalk
It's bigger - has more surface area - would help with porpoising, water pressure possibly and hole shot...always thought bobs was too small...the fin I had on the ghost was bigger than a bob's...the waiver is to keep from being sued for some dillweed installing it wrong and screwing up their
boat...just a cya thing
Re: Caviataion Plate
Posted: August 29th, 2009, 4:09 pm
by wevans
Re: Caviataion Plate
Posted: August 29th, 2009, 5:00 pm
by Redbelly
You guys ain't fishin today?
Re: Caviataion Plate
Posted: August 29th, 2009, 6:42 pm
by Chalk
Redbelly wrote:You guys ain't fishin today?
What is this fishing you speak of ?
Re: Caviataion Plate
Posted: August 29th, 2009, 7:21 pm
by rocket
Launched the Duracraft at the Fort to find my steering was froze up. Worked fine last week

Somebody call Wavel and tell him I'm headed his way Monday

Re: Caviataion Plate
Posted: August 29th, 2009, 7:59 pm
by Reel Cowboy
Chalk wrote: the waiver is to keep from being sued for some dillweed installing it wrong and screwing up their
boat...just a cya thing
Might be but seems dang excessive to me. But I just sell stuff that is pretty much a bomb looking for a reason to go off.
Re: Caviataion Plate
Posted: August 29th, 2009, 10:07 pm
by rocket
Chalk wrote:the fin I had on the ghost was bigger than a bob's.
I had a Bob's on the G3 tunnel, and really could not tell a difference. It might have been me, but nothing stood out. On the Duracraft tunnel, it is very similar to the G3, where the boat does not "sit down", but rather comes out, and on to a plane gradually. So I'm not looking for an improvement on the hole shot.
At WOT, I can barely trim the motor w/o it starting to porpoise. And I get 34/35 mph at WOT. Not that this is a compliant, but I would like to get a little more of the boat out of the water to reduce any plowing, then MAYBE gather a few more mph (not that it really matters, I know this boat is not a speed boat).
My other concern is keeping water around the prop to keep pressure up, and cut out the blow out element.
These are the reasons I'm inquiring about a bigger plate than Bob's offers, but don't know anyone who has had any other kind of plate.
Chalk, what did you have on your boat?
Re: Caviataion Plate
Posted: August 29th, 2009, 10:17 pm
by Barhopr
look into a heavily cuped 4x prop and some trim tabs. take that damn plate off the foot.
Re: Caviataion Plate
Posted: August 29th, 2009, 11:52 pm
by Reel Cowboy
Barhopr wrote:look into a heavily cuped 4x prop and some trim tabs. take that damn plate off the foot.
Brotha Brock speak da truff.
Re: Caviataion Plate
Posted: August 30th, 2009, 8:12 am
by Chalk
Porpoising on a flat bottom boat is the nature of the beast.....to eliminate porpoising at WOT weight forward is the cheapest option. Try putting a cooler full of water forward and see if it doesn't reduce it. Not saying to carry around a cooler of water, but you can move your drink cooler or add a storage cooler. It will make a difference - ask Birddog cause that is the experience I am basing my comments off of the time it took him to get his to quit porpoising at WOT. He moved two coolers and three Group 27 batteries forward.
The fin will help on a standard boat with porpoising but I think it will not help much with that on a tunnel. Due to the fact the water column is brought up to the motor with the tunnel. The plate would/should improve your water pressure and help with any cavitation by compressing the water that comes up from the tunnel. Bobs plate is too far aft on the motor to help with the water pressure. This plate surrounds the entire foot and that is how it helps with water pressure and cavitation by pushing all and any water pushed up back down.
Try some weight forward first before you start spending any money - my Banshee will porpoise at WOT by myself add some fat ass like Jumptrout upfront and it stops. Move some weight forward- ezpz
Re: Caviataion Plate
Posted: August 30th, 2009, 10:19 am
by rocket
I'm afraid I can't get any more weight forward. The only storage is forward, so that houses my 2 Group 27's, then all gear. I usually have 2 coolers forward (drink/fish) as well. Gas tank being in the rear doesn't help at all.
I've also been told the motor being mounted too low will cause the porpoise effect, but the jack plate should fix that easily. However, we are back to the blow out I'm concerned with, so maybe the bigger plate to keep water around the prop is the way to go.
She doesn't porpoise at WOT, only at WOT and when I trim her up some to reduce plowing. I might get to bump the trim up once or twice, anything more then it starts.
Re: Caviataion Plate
Posted: August 30th, 2009, 10:35 am
by Chalk
I can't see how your plowing and can have porpoising...mine can be porpoising and I have to trim tabs down which makes the boat plow and stops the porpoising. Do you need to trim or are you not reaching your RPMs?
Blow out will happen...I added a Powertech prop with a lot of cup and can only go 4 inches before blow out...but I start loosing pressure and cavitating too...so I can't go much higher.
If you jack it up and then start trimming...you have to jack down a little for the elevation...I jump out of the hole and start jacking up...once I get the motor up to 4 inches I start trimming....if you trim much you need to bump the jack plate down a hair...its a give and take...I could only bump trim about twice on my ghost before it would start porpoising...I would either drop the jack plate or trim in to stop it.