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Old 10 April 2024, 17:47   #1
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Zodiac MK5 - new owner info

I recently acquired a 2001 MK5, and plan to do a refresh on it. Will be running it initially with a 60hp Tohatsu.

While I've downloaded some official Zodiac owner's manuals, I'm wondering if anyone has a) an official USN (or similar) operations manual for these boats, and b) if there's any go-to source for more specific vintage MK series info (threads, other web site owner groups, etc). Looking to learn what I can.

Thus far the boat looks pretty serviceable. Some slow leaks, but transom and attachments thereto look good. Haven't had it on the water yet.

Also curious if anyone has any personal experience dialing in the motor height with the MK series V hulls. Where should cavitation plate be situated, and to what do you measure/align?

And are these hulls tending to benefit from adding a hydrafoil?

FWIW, I am in the States, and notice many users on RIBnet are UK/Euro. If there's a N. American group I should plug into, too, please point the way.

Oh...any pressure gauge recommendations for these valves? My current ones don't fit, and with 25" tubes it seems easy to underinflate it.

Cheers,
RTC
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Old 12 April 2024, 14:07   #2
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I have a pump with a built in pressure gauge. Sent you a PM so I can email a couple pdfs that might help.
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Old 12 April 2024, 14:13   #3
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Thanks, Chris. I use a Big Red Blower to fill the boat, but suspect it can only get the tubes to ~1.5-2psi.
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Old 16 April 2024, 21:44   #4
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Looking over the new (old) boat, it seems to be in fairly good shape. The transom has some light cracks in the glass, and the rubber has a few patches needing reglued. All valves have hard/cracked gaskets, and will be replaced, along with some of the caps.


There is a leak in one speed tube's seam, which will take a bit more investigation. For the price, it seems to be have a lot of life left in her.
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Old 24 April 2024, 02:07   #5
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New valves all around.
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Old 24 April 2024, 02:20   #6
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Yesterday I decided to check the transom for leaks. After jacking up the trailer tongue with a floor jack, I used a garden hose to add 4-5gal in the stern. No immediate signs of leakage. Two of the self bailers did weep. PO had installed plugs, so they are not set to bail anyway. The weeping stopped after snugging up the nuts. With time, another slow leak appeared, and hints at a seam between floor and the tubes. Slow as it is, the trailer doesn't allow easy locating of the problem spots.

Perhaps with the speed tubes and keel, assuming a moderate payload, there will be little infiltration anyways. For now, I am mostly curious about how much the new valves resolve slow leaking. Sadly two of the new valves leaked. They look like knock off's, and perhaps not genuine Zodiac parts. Has anyone known there to be non-OE valves on the market?
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Old 24 April 2024, 08:47   #7
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I've had several SIBs with this valve type including on the HP air floor of my current one. They are quite crude in design you might say but have been very reliable and so much easier to clean of any debris than just about every other valve type.

Where are yours leaking... a bit of by-pass on the valve flap or the cap?

Re genuine or not. I've bought from both Zodiac dealers and RIB repair places listed as OE. They don't always come in a Zodiac labeled bag, sometimes like yours in a plain bag with the part number in marker pen.
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Old 24 April 2024, 15:01   #8
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Quote:
Originally Posted by Fenlander View Post
I've had several SIBs with this valve type including on the HP air floor of my current one. They are quite crude in design you might say but have been very reliable and so much easier to clean of any debris than just about every other valve type.

Where are yours leaking... a bit of by-pass on the valve flap or the cap?

Re genuine or not. I've bought from both Zodiac dealers and RIB repair places listed as OE. They don't always come in a Zodiac labeled bag, sometimes like yours in a plain bag with the part number in marker pen.
It's slipping past the valve flap on 2 of the 5 new ones. Adding cap helps, but obviously the valve itself should be sealing. I just installed them, so would be surprised if any debris is caught, but will check.
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Old 24 April 2024, 15:08   #9
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The gauges Zodiac supply rely on a little by-pass of the flap to get a reading. Pretty well all the SIBs I've had relied on the cap as the final seal.
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Old 24 April 2024, 15:14   #10
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Quote:
Originally Posted by Fenlander View Post
The gauges Zodiac supply rely on a little by-pass of the flap to get a reading. Pretty well all the SIBs I've had relied on the cap as the final seal.
Interesting. I am new to these and similar valves, but assumed the gauges used a tab to push aside the flap to allow pressure to reach them. It seems the flap, when untouched, should fully seal.

I bought a couple new caps, too, and will use them on these weeping valves to play it safe. Some soapy water should tell if anything is sneaking past.

I was also told that these intercommunicating valves have an integrated pressure relief system that will relieve psi beyond the ~3.5psi max. I've yet to find a really good overview video discussing all the features, functions and nuances of the MK's unique valving system as a whole.
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Old 24 April 2024, 16:15   #11
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I had a 70s Zodiac with these valves and its original chrome pressure gauge. It just screwed onto the valve and the reading built over a few moments due to pressure passing the flap (too little to hear).

Similarly my current Zodiac/Bombard has an OE gauge and that is just a taper push fit into the valve relying on the bypassing pressure to give a reading.
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Old 24 April 2024, 16:19   #12
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Quote:
Originally Posted by Fenlander View Post
I had a 70s Zodiac with these valves and its original chrome pressure gauge. It just screwed onto the valve and the reading built over a few moments due to pressure passing the flap (too little to hear).

Similarly my current Zodiac/Bombard has an OE gauge and that is just a taper push fit into the valve relying on the bypassing pressure to give a reading.
Good to know. I appreciate the beta. I'm used to old military screw valves and various Leafields.

I gotta say the dramatic pressure changes of a black boat are something that's taking some getting used to, vs our lighter colored boats.
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Old 24 April 2024, 16:53   #13
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Quote:
Originally Posted by Right Turn Clyde View Post
I was also told that these intercommunicating valves have an integrated pressure relief system that will relieve psi beyond the ~3.5psi max. I've yet to find a really good overview video discussing all the features, functions and nuances of the MK's unique valving system as a whole.
Maybe not the best video, but it's 7 years old and the camera doesn't capture everything, but he does a full strip down of the intercommunicating valves as part of the service. These valves were widely used on Zodiac GR (Grand Raid) boats.

For the machined parts (intercommunicating valve) - you can use a little marine grease, but anything with rubber, especially valve caps, then I'd use a specific red grease, similar to what I use on brake rebuilds. It doesn't swell the rubber or gaskets. You will need valve tools for this procedure.



Incidentally - try to keep the Delrin nickel valves, they are superior to the plastic ones, but you do need to be on top of them in terms of maintenance. Unfortunately they are not cheap, but the rubber gaskets aren't too bad.
https://www.zodiaconlineshop.nl/en/spare-parts/valves/

If your inflatable keel is leaking, I will put money on either the valve itself, or more likely where the keel tube is doubled over (at the transom end) and thermo-bonded. You can repair.
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Old 24 April 2024, 17:00   #14
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Thx. I'll watch that video. I'm curious to learn if there is an "off" or closed position, as I seem to have hit one where the blower isn't adding any air.

I only used the nylon caps on the speed tube hoses, replacing them along with those nylon valves. Definitely keeping the nickel bits.

Keel is fine, but starboard speed tube is leaking (seam near the stern it appears). These things weigh a bit, so not so easy to just tip up and work on the bottom.

Has anyone found replacement rubber flat gaskets for the bottom of the valves, where they interface w/ the main intercomm valve body? Those are what wore out, and I'd love to source replacements to keep them as spares.
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