Hi Jerry.  Conversion to LPG is mixed depending on the age of your stove.   At best your only replacing the orifices for ones with a 30% smaller hole.  Worst case is whole new stove.   Then LPG tank storage, which requires dedicated storage with bottom drains to outside the boat (ABYC has more info on requirements).  I carry 2 6lb aluminum tanks on the stern. Ugly but works on my Mk1.   

I can usually be found at Skuttlebuts most Wednesday from 3-5.  Their happy hour is not as good as it was but still ok.  Ask for Bob’s table.  

Suremarineservice.com is great vendor for this type of service.  
 

Jerry - I did this conversion several years ago and have not regretted it.  We replaced the stove as I could not find orifices for my old CNG unit and it had seen better days any way. I built a box in the center of the aft lazerette with solenoid, sensor and drains all accounted for. Some pics here: https://www.catalina36.org/forum/technical-discussion/mk-1-propane-conve...
There are other pictures on that thread of a production housing used by the OP.  You might be able to contact that member for more information too.
His installation seems to take up a lot less space than mine.

Jerry -
Are you sure CNG isn't available anymore in your area?  See www.corpbrothers.com/ma0502/marine/cng-dealers.php#washington
We're still able to get refills (albeit not cheap, around $80 for an exhange) from this company in the north-east US, via some marinas.  
We seem to get about 1 full sailing season (including about a month of cruising) out of a tank, and have a spare just in case.

I've also contemplated putting together one of those devices to refill at service stations that sell CNG
( www.c34.org/wiki/index.php?title=CNG_Refill_Adapter ), but I'm a little skittish about the idea.
Here's a video of someone using one: www.youtube.com/watch?v=OfChHyrV4PE

But long term, I think we want to do this conversion at some point, for sailing out of our region.  Largest impediment seems to be the tank locker location, however, particularly on older boats like ours...  Maybe lowering the lazarette floor on one side of the steering quadrant might work?  In any event looks like it will need to be a custom built locker.

 

My MK1 had cng when I got it, with about 2000 psi in the tank. It didn't seem to last very long in comparison to the small propane tank on our previous C30, and my wife wanted a larger 3 burner stove with a larger oven. After reasearching, I learned it was possible to change the burner orifices to use propane, but the ofifice on the oven control is a fixed size and cannot be modified for propane. I collected all the stuff to make the cng adapter described in that other post. Kind of a pain since everything can't be sourced from the same place, and it does require a good machinist to modify the thread on one end of the T fitting from a pipe thread to a straight thread with a recess for a sealing o ring. Used it once. Kind of freaky with the amount of pressure involved and the fact that I was completly alone in the place.Just hook it up, put in the credit card and pull the lever. With all the picky regulations about filling a propane bottle to about 200 psi, there were no restrictions in place for a 2800 psi fill. It filled in what seemed about 3 seconds and only cost a few dollars. Apologies for going off topic some. I ended up getting a 3 burner propane stove, fabricating a back rail mount for a larger composite propane tank with external regulator and solenoid, and all nice new propane hose. The hose goes thgough a sealing bulkhead fitting on the stern in one continous run to the stove fitting.IMHO a propane locker is just an expensive PIA, limiting tank size and taking up valuable locker space.

After replacing my cng stove with a force 10 2 burner which fits perfectly, I mounted the slim line 6lb propane canister inside a fender (top of fender cut off) which is held on the port side of the pushpit with a single fender holder bolted to the pushpit. Works great! Leaves my lazarette free for various other stuff. I was pushed for time when I had to do this and did not have enough time to design and fabricate an enclosure inside the rear lazarette. I will post a photo when I get back to the boat in a weeks time.

Sure Marine Services caries a nice rail mount system for holding tanks, regulator and selonoid http://www.suremarineservice.com/Galley/Propane-Railmount-Bracket-Assembly/

I saw that rail mount but the $45 cost of the stainless fender holder seemed convincing to me. I had a new fender which i found floating about after a storm which is a perfect fit. Also the fender completely protects the gas cylinder from sunlight which causes the raw aluminium to look shabby after a while. I mounted a breaker to the left of the cooker in the cabin and I enshrouded the gas cable with spiral conduit for sun protection. I am in Scotland right now returning next Friday so will post a photo or two next Saturday.

My boat came with the cylinders in a stainless fender holder bolted to the stern. One of my next projects is to make a Al holder and skin it in starboard. I reciently installed a propane detector under the galley floor. I have yet to connect to the selonoid ground. Les

I was faced with same dilemma.  My 1985 stove manufacturer is no longer in business.  To redo the stove, plumbing and storage was going to several thousands of dollars.  My solution was to buy an adapter for filling the tank at a CNG gas station.  I live in Michigan and was able to find a reliable site.  The average cost of a fill up is under $2.00 per tank.  I have two tanks, I purechsed a second tank in 2008.  We normally cruise for about 6 or 7 weeks on the Great Lakes. We CNG for both the galley stove and grill.  I typically go through 1-1/2 tanks a season.  The tanks themselves require a hydrostatc test every 5 yrs.  Last season I had it done through a local suba shop who outsources the work.  The cost was $48 or $9.60/season per tank.  The rig was expensive $400 in 2016.  However, I have paid north of $70 per tank.  Since 2016 I have paid less than $110 for the fill ups and Hydrostatic testing.  When CNG was readily available, $35 dollars a tank was the norm, roughly $50 per year.  I'll have a few more years to break even on the sunk cost, but the replacement cost was avoided.  In my mind a big win.

By the way my wife feels much safer with cng than propane.  CNG leaks up.

I'm attaching a file that id's the seller of the rig.  Hope this hepls.

Lou Bruska
Sojourn Hull 495
CNG fill adapter_Page_1.jpeg