For several years now I have heard the debate among sailors about using generators on their boats, especially the Honda 2000 generator which is affordable and can drive most of your boats energy needs like air conditioners, battery chargers and hot water. Many argue about gasoline storage, noise and the dangers of Carbon Monoxide (CO). Others like the convenience of energy on their boat beyond solar and wind especially in hot climates and lack of utilities for mooring and anchoring. I have never bought the "danger" issue of gasoline storage and CO because CO meters are readily available at low cost and we have been using gasoline on boats for a hundred years. We heard much of the same "safety" arguments many years ago about propane but we now use propane on our boats on a regular basis with little safety concerns. Solar and wind generators are expensive and you will never get these energy sources to run your A/C. A 3.5 to 4.2 KW diesel generator installed is always over $10,000 and takes up a lot of room and they do not guarantee the sound level when they run at 3000 RPM.
[B]The real issue is noise both to your boat and to your neighbor's boat.[/B]
I wanted to use my Honda 2000 on my Catalina 375 sailboat to run its air conditioner, charge the house batteries, and make hot water but not all at the same time. The Honda 2000 has sufficient power to do these individual functions one at a time. The Honda 2000 is quiet but it is still too noisy for most people when running at full load sitting on your boat’s swim platform or fore deck. I designed an enclosed sound proof box for the Honda which used a specially designed wet exhaust system to dampen the exhaust noise and direct the wet exhaust to outside the hull just above the water line. The sound box was custom built into the starboard stern lazarette just above the diesel fuel tank, see attached picture. In addition to the wet exhaust cooling I installed two 3" inline blowers that were powered from the Honda 12V output plug. These blowers sucked hot air from the sound box out through the stern vents and to the open air.
The sound reduction was substantial producing the following sound tests. At anchor with no generator running the cockpit area showed general ambient background noise at 47db. Start the Honda, put under full A/C load, and leave the sound box lid off (Honda exposed to open air, with the meter next to the sound box) showed a reading of 68 db. Place the sound lid on the box and place the meter on the hatch lid, the reading was 53 db. Walk around the cockpit and the reading was 51-52 db. Sit out on the foredeck, and the reading was 48 db. Below decks in the salon with full A/C load the reading was 51 db, in the aft cabin 52 db and in the V-berth 49 db.
How you cool the Honda 2000 in its sound box is complicated engineering and the specs are are attached in a PDF format.
You can have quiet energy on your boat for reasonable cost and be safe.
Rod Tennyson
C-375 #16
| Attachment | Size |
|---|---|
 honda generator installation technical specs.pdf | 38.94 KB |
Very creative Rod. Have you confirmed with your insurance broker that your insurance is still valid with that setup?
Tom Irwin
North Saanich, BC, Canada
1983 Catalina 30 - #3134
Until June 10, 2013
Future Catalina 36 MK II owner
No, I have not discussed any insurance issues with my agents but the policy has no exclusions on any modifications to the boat whether generators or anything else.
There are no less the 4 CO meters on my boat all connected via a wifi system including one in the sound box. Any CO reading over 50 ppm sets off all the alarms and an electronic voice tells you where the reading comes from.
The gasoline tank for the Honda is a five gallon external tank located in the segregated stern gasoline storage area on the C-375. The Honda also sits in a fluid tight tray with an external drain to the outside hull in case of any spills.
Rod Tennyson
Lila Jean C-375
Rod did you fabricate the extended wet exhaust system ? Did you fabricate The external fuel system?
Does the wet exhaust replace the standard dry exhaust ?
Tom Irwin
North Saanich, BC, Canada
1983 Catalina 30 - #3134
Until June 10, 2013
Future Catalina 36 MK II owner
Tom, I did fabricate the wet exhaust. The Honda wet exhaust muffler was the most difficult part of this project due to the special brazing rods needed to fabricate the copper tubes to the Honda steel muffler at just the right hot
spots on the Honda exhaust system. See attached pictures of Honda stock muffler and the modified wet exhaust. I change the stock muffler to the wet muffler for the boat and change the wet muffler back to stock when using the Honda on land.
The large hose is the wet exhaust which connects to an exhaust hose leading outside the hull exiting about 8" above the waterline. The smaller hose is the intake raw water. The wet muffler is a "simple" heat exchanger in which salt water never comes in contact with the steel muffler. The salt water never leaves the copper tubing and the salt water exits deep down into the lower end of the large rubber exhaust hose to prevent and back suction into the muffler. I installed a mixer at this point in the hose to mix up both water and exhaust for cooling and lower sound. The trick was the high content silver brazing (1000F melt) to make sure I had good metal to metal contact between steel and copper for good heat transfer. I have attached zincs to the muffler to protect for
corrosion (not shown on the picture).
I purchased a standard second gas tank system for the Honda to place the 5 gallon external tank outside the sound box, which is stored in the segregated stern gasoline storage area on the C-375.
Unlike built in diesel generators at the end of the sailing season I just pull out the Honda from its sound box (while by boat is in storage) re-install the stock muffler, do a thorough inspection and use the Honda for camping or power outages. If it needs repairs that I cannot do I just take it to the
Honda dealer, much cheaper than marine diesel mechanics that have to come to your boat.
Nice job Rod, very creative and a lot of good info there. I sent you a PM re: I'd like to make this into a tech article for the website. If you have a sec please let me know if that's OK with you.
I'd like to know if one could fabricate the wet exhaust without specialized tools...
---- Howard & Linda Matwick ----
--- S/V "Silhouette" - Nanaimo, BC ----
--- 1999 C36 MkII #1776 M35BC ---
After searching for a specialized metal fabricator for over a month I gave up and decided to do it myself. I have had some experience with oxygen/ acetylene torch welding and brazing but brazing copper to steel is more difficult requiring high silver content brazing rods (expensive). I tried using Map gas with Oxygen (Home Depot) and finally completed the job (took 5 small bottles of oxygen)but you really need the heat of acetylene. You are better off to try and find an experienced oxygen/ acetylene torch welding and brazing specialist who has had experience with dissimilar metals.
My materials cost was about $400:
Honda stock muffler $139
Honda stock exhaust pipe $56
3 silver brazing rods $146, you may need more
copper fittings $32
1/4 copper tube 4 ft $4
3/8 cooper tube 4 ft $5
Wet exhaust hose Gates Vulco-Flex Coolant house 1.120 ID 12" long $14