Reply
 
Thread Tools Search this Thread
 
Old 01 December 2009, 17:51   #1
Member
 
Peter_C's Avatar
 
Country: USA
Boat name: Uh...a kayak?
Length: 4m +
Join Date: Dec 2009
Posts: 1,485
Weird! Zodiac arches it back then cavitates

I have put a few hours on my new to me Zodiac which is a MKII HD.



It was all going good until we hit this problem.



Then it started doing something I have never felt before. Of course it is the first time I have driven it fully loaded on glassy water. When running full throttle at 23.4 mph or so, what it does is arch it's back so to speak, then unloads picking the transom up out of the water a little. This causes the motor to cavitate for a second. Then it starts the process all over again and releases about 20 seconds or so later. If I slow down to around 19 mph or thereabouts it does not do this. We tried moving people around both forwards and backwards with no results. It seems like it is an air pocket forming or something. Not really an issue since the Pacific Ocean is never dead flat, and diving a lake is something we will not be doing anytime soon.

Anyone else experienced this?
__________________

__________________
Peter_C is offline   Reply With Quote
Old 02 December 2009, 18:01   #2
Administrator
 
John Kennett's Avatar
 
Country: UK - England
Town: Brighton
Length: 3m +
Join Date: May 2000
Posts: 6,829
Hi Peter

You've posted links to some pictures on scubaboard.com but they won't show here. You will need to upload them as attachments.
__________________

__________________
John Kennett is offline   Reply With Quote
Old 03 December 2009, 02:43   #3
Member
 
Bigmuz7's Avatar
 
Country: UK - Scotland
Town: Glasgow
Boat name: stramash
Make: Tornado
Length: 5m +
Engine: Etec 90
Join Date: Feb 2006
Posts: 5,068
I have , although not in that particular boat, shifting weight usually sorts it for me, so I can get the bow up a bit, make sure your engine trim stop, isnt set too low if it has one, and also that your tubes are at the right pressure, of even if you think they are, try making them a little firmer to see if it helps
__________________
Bigmuz7 is offline   Reply With Quote
Old 03 December 2009, 09:09   #4
Member
 
Country: Canada
Town: British Columbia
Make: Gemini
Length: 4m +
Engine: 40hp 2 str
Join Date: Oct 2003
Posts: 2,151
How many psi are you inflating the main tubes and the keel to?
__________________
prairie tuber is offline   Reply With Quote
Old 03 December 2009, 10:21   #5
Member
 
Country: UK - England
Town: Bristol
Make: Ribcraft
Length: 5m +
Engine: Yamaha
Join Date: May 2006
Posts: 4,194
if the driver and passengers would sit right in the middle, the problem would go away,

the keel is not deep enough, try it
__________________
matt h is offline   Reply With Quote
Old 07 December 2009, 22:17   #6
Member
 
Country: USA
Town: Havre de Grace, MD
Boat name: SD430
Make: Saturn
Length: 4m +
Engine: 25hp 2 stroke Merc
Join Date: Jul 2009
Posts: 45
Send a message via ICQ to 1ThOFA87
I have the same problem. Mostly when I have my brother aboard. He's pushin' close to 400 lbs and I've had him sit about mid front center and mid starboard. I'm 200 pounds so he's double my weight and I can't find anyplace to sit hiim without this problem. I'm going to get an electric pump and see if it gets my tubes firmer than I can with my foot pump.
__________________
1ThOFA87 is offline   Reply With Quote
Old 08 December 2009, 00:08   #7
Member
 
Country: Canada
Town: British Columbia
Make: Gemini
Length: 4m +
Engine: 40hp 2 str
Join Date: Oct 2003
Posts: 2,151
Just in case I hadn't asked earlier;

How many psi are you inflating the main tubes and the keel to?
__________________
prairie tuber is offline   Reply With Quote
Old 08 December 2009, 19:35   #8
Member
 
Country: USA
Town: Havre de Grace, MD
Boat name: SD430
Make: Saturn
Length: 4m +
Engine: 25hp 2 stroke Merc
Join Date: Jul 2009
Posts: 45
Send a message via ICQ to 1ThOFA87
Quote:
Originally Posted by prairie tuber View Post
Just in case I hadn't asked earlier;

How many psi are you inflating the main tubes and the keel to?
I don't know about Peter but I have no idea about mine. I have a footpump and fill it until it won't take anymore air. What should they be inflated to?
__________________
1ThOFA87 is offline   Reply With Quote
Old 08 December 2009, 20:41   #9
Member
 
Country: Canada
Town: British Columbia
Make: Gemini
Length: 4m +
Engine: 40hp 2 str
Join Date: Oct 2003
Posts: 2,151
Main sponsons should be 3.4 psi, the keel just a bit higher. I would highly recommend getting a guage, proper inflation pressure is critical to the performance of the boat.
__________________
prairie tuber is offline   Reply With Quote
Old 13 January 2010, 02:33   #10
Member
 
Peter_C's Avatar
 
Country: USA
Boat name: Uh...a kayak?
Length: 4m +
Join Date: Dec 2009
Posts: 1,485
LOL I forgot I posted this thread.

I keep the all of the tubes set at the spec written on the transom. My pump has a gauge on it, although it is cheesy.

Over the new years holiday it actually did cavitate on the Pacific Ocean because it was glassy flat inside Monterey Bay. Again we tried moving people around to no avail. I plan to buy a really nice gauge to make sure I am pumping to the proper pressures.

Also found out with four divers and six scuba tanks onboard, the boat takes awhile to plane.
__________________

__________________
Peter_C is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 16:39.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.