Damn Donzi: my hatch keeps popping open

[John C in PA]

Driving home from a recent launch my hatch popped open at 45 MPH . Nothing broke. The turn knob had about 1/8" play when latched and I figured when bouncing along on the trailer the cross pin bounced out of the indentation in the cast latch body. So I installed a large rubber gasket between the bottom of the knob and the hatch. Nice and tight.

Today the lake was pretty riled up and while slamming around at 55 MPH the hatch flew up . Again no damage; I used some para cord to secure the hatch closed for the rest of the day.

I'm thinking for a no cost solution I can file the indentation in the latch for the cross pin so it seats deeper. Or I can add some hood pins. Not expensive, but try and find a kit with all SS parts; there are some aluminum kits though.

Any suggestions guys?

John C in PA

[Conquistador_del_mar]

Your idea to file the notches deeper sounds plausible, and I think you might also want to stretch the spring or get a stouter spring to add more constant pressure. My 1971 hatch has never popped out of place, but it takes a little downwards effort to latch it. Bill

[gcarter]

This may be a silly question, but is the spring and washer under the knob and on top of the hatch?
McMaster Carr offers the confined space conical compression springs in various diameters and tensions. http://www.mcmaster.com/#compression-springs/=nsx3il

[pipnit]

This may be a silly question, but is the spring and washer under the knob and on top of the hatch?
McMaster Carr offers the confined space conical compression springs in various diameters and tensions. http://www.mcmaster.com/#compression-springs/=nsx3il

yup, replace the spring, I used to have the same problem. After replacing the spring, I didn't swedge the pin in there well enough and it moved which kept me from opening the hatch at all! Eventually I was able to push the pin through, then I drilled and tapped a hole for a small allen set screw for that pin. Good luck!

[Ed Donnelly]

Put a monster supercharger with 2 -4barrels on the engine then you won't
need the hatch ...Ed

[Bobby D]

John,
All good suggestions, and If your set up is like the one I have the holes in the bracket are slotted and you may need an adjustment. When I replaced the mill last year I made a new wood bracket to replace the old one. Like Bill’s mine is tight and takes a little effort to open.
Bob

[John C in PA]

Your idea to file the notches deeper sounds plausible, and I think you might also want to stretch the spring or get a stouter spring to add more constant pressure. My 1971 hatch has never popped out of place, but it takes a little downwards effort to latch it. Bill

After I installed the large rubber gasket the knob is fairly hard to completely turn so the cross pin is seated. I can confirm when I left the dock it was seated as I like to check the bilge before a startup.

This may be a silly question, but is the spring and washer under the knob and on top of the hatch?
McMaster Carr offers the confined space conical compression springs in various diameters and tensions. http://www.mcmaster.com/#compression-springs/=nsx3il

George, the 1/8" rubber gasket is under the knob, then the spring, then the scuff plate. Below the hatch is the large SS washer and the cross pin. Is the order correct? See pix attached.

Put a monster supercharger with 2 -4barrels on the engine then you won't
need the hatch ...Ed

Smartass

John,
All good suggestions, and If your set up is like the one I have the holes in the bracket are slotted and you may need an adjustment. When I replaced the mill last year I made a new wood bracket to replace the old one. Like Bill’s mine is tight and takes a little effort to open.
Bob

Bob, the wood block is partially split but its below the latch attachment screws (which I replaced last year). See pix attached.

[Carl C]

My hatch knob started turning to the open position by itself but the hatch never blew open. The hardened pin rubs on an aluminum catch. If you do not push down before turning the latch then it wears the aluminum until the notches are nearly gone. I filed the notches just a bit and make sure that no one opens the hatch before pushing down on the knob. Problem fixed.

[gcarter]

Mine came apart so many years ago I couldn't remember what the arrangement was, in fact I'd lost the spring and washer.
I bought more springs and washers, and even polished the washer a bit. I put together like this: knob w/spring and washer on the hatch. Underneath is a much smaller washer, then the pin.

One thing I never cared for was the wooden block where the bracket was screwed into the end grain of the wood. It seemed to me that it was guaranteed to fail.
I mounted my latch bracket to a 2" long piece of 4" X 4" X 3/8" aluminum angle that I carefully trimmed.
Here's a picture of it:

[John C in PA]

[QUOTE=gcarter;641864]Mine came apart so many years ago I couldn't remember what the arrangement was, in fact I'd lost the spring and washer.
I bought more springs and washers, and even polished the washer a bit. I put together like this: knob w/spring and washer on the hatch. Underneath is a much smaller washer, then the pin.

George, that's the same sequence of parts my rig came with. I assume its correct however after 20 years who knows if a PO may have changed the order.

My hatch knob started turning to the open position by itself but the hatch never blew open. The hardened pin rubs on an aluminum catch. If you do not push down before turning the latch then it wears the aluminum until the notches are nearly gone. I filed the notches just a bit and make sure that no one opens the hatch before pushing down on the knob. Problem fixed.

Carl, I'm starting to think this may be the problem. Since installing the gasket I had to push down fairly hard on the knob to get the cross pin to snap into place. This should have kept the knob from turning but apparently it didn't. So perhaps the groove is worn shallow. I'll post again later.

John C

[Carl C]

My '05 does not have a wood mount. It uses an aluminum angle iron to bolt the catch to.

[joseph m. hahnl]

I don't think I have that much slop in my hatch pin.

[John C in PA]

My hatch knob started turning to the open position by itself but the hatch never blew open. The hardened pin rubs on an aluminum catch. If you do not push down before turning the latch then it wears the aluminum until the notches are nearly gone. I filed the notches just a bit and make sure that no one opens the hatch before pushing down on the knob. Problem fixed.

Ding, ding, ding. We have a Weiner, oops Winner. The cross pin seating nitch is fairly worn and I can turn the knob to "open" as easily as to "lock" position. Good call Carl.

DSC00223.JPG

Update: I filed both of the grooves with a rattail file so they actually have a square (not rounded) shoulder now. In addition, I found out that the groove closest to the seats (lower one in the picture) was shallower than the other groove so basically the crosspin was only setting fully in one shallow groove. Now when I fully turn the knob I can feel the cross pin drop into the grooves.

[silverghost]

This seems to be a common problem with that rough aluminum latch receiver casting.
It is just not filed out deep enough for the split roll pin latch ~~~
I just bought a new unit and it is also machined higher on one side than the other & the latch groove very shallow.
Like you~~~I filed it much deeper on both sides.
The new aluminum latch receiver came with a slotted aluminum angle bracket to replace that old wooden block under deck receiver mount.

The other common issue is the "Donzi Knob" latch roll split pin shifting slightly to one side thus preventing you from getting your hatch open.
This can be a real problem to get the hatch cover open when this happens !
I like the small set screw idea locking the pin in the equal center position .
A drop of Locktite #271 or #242 on the pin before installation might work also to keep the pin centered ?

On my old 18 project's hatch there was a large round starburst stress impact crack in the hatch's fiberglass where in the distant past the hatch must have come unlocked and it suffered a violent aft blow-over smashing into the aft lifting ring ! It's a wonder the hatch cover itself did not blow-off the boat's deck !
I guess these "Donzi Knob" hatch latches have been causing problem issues for decades ? !

[John C in PA]

I just towed 5.5 hours at 65-70 MPH and the knob was firmly sest at each stop we made. As I mentioned previously, you can now feel the cross pin snap into place whereas before the knob just turned until it stopped.

John C