98 model 405 hot water heater

[Midnightsun]

Jumping in way too late on this but here are my 2 cents. After 22 years it is time for a new tank. We replace them at home every 10 years or at least this is what they recommend so why would you think after 22 years things will be fine? It probably heats OK but if you look inside you will see a disaster waiting to happen. All these tanks or the vast majority of the affordable ones have cylindrical aluminum tanks inside that contain the water, they oxidate/corrode and build up crude inside which contaminates the entire system with particles and other crap. I replaced my unit last year after only 10 years because after internal inspection I was shocked from what I saw. Only way I realized there was an issue is it would practically not drain any more during winterization, basically a dribble with drain valve wide open and yes I did flip open the relief valve for faster drainage. Reason was there was so much sediment blocking the valve which is basically tank corrosion material!

None of these tanks to my knowledge come with an anode yet they are offered as an option that can be added. I did add one plus a sediment filter to catch any particles that may erode from the sacrificial anode. A plastic sediment filter will not work as this is hot water so be careful in what you choose. Here is a link to the thread. viewtopic.php?f=11&t=3660&p=24627#p24627

[Serendipity]

I agree with everyone and thanks for the insight. Since the fresh water tank has to come out to replace the 11 gallon hot water heater. I am going to pass on removing it at this point. Just replace the pressure relief valve part #73127 which is the old number for Seaward but I found them.

I am replacing some of the dry hard hoses with similar hoses meant for hot and cold potable water that I can reach. Probably will just leave the strainer alone since it looks clear inside and it was connected to the fresh water tank. It did have the stainless screen and gents, this 405 simply wasn't used the first 20 years of its life. 3 owners, 300 hours and I was told it was on a engine program where they simply started the engines every 2 weeks to a month, which may or may not have happened. Granted things can and do go wrong just sitting. It has been my experience with automobiles they go down faster, but as long as it will give me some hot water I am fine.

But the harbor master said the couple owners going back to 2005 rarely visited the boat because it was too much for them to take out.
I have spent over $15,000 updating the engines, bilges,blowers, fluid changes, detail, bottom painted, hell I even replaced the fuel injectors to make the trip home. Then I spent another $18,000 plus driving her home over 7 days. This included a 200 mile road trip where the top had to be disassembled to transport, then reassembled at a cost of $10,000.

Yet I haven't driven the boat since July 4th of last year in a warm climate where we have year round boating and I work all the time( my choice-self employed). This slow down has been great for me personally and we did grill out on the pier last weekend. Lol

So she sits on a fresh water lake in a covered concrete slip connected to all the necessities of life.

I have told my wife of 24 years, if we don't use the boat this summer, the 405 goes on the market next spring, although I have no clue what to ask for her after all the updates.

Just a gorgeous boat to let her sit anymore. I have 477/470 hours on her so time will tell and thanks to everyone for the information. Ya are the bomb.

[g36]

X2 on catching any sediment from the water heater. Gets trapped and sink aerators etc. My 405 sat alot for her early years shame you have spent so much money on her. I love my 405 but it would be hard to keep spending money and get no real enjoyment . Good luck.

[Serendipity]

G36
This is my first yacht other than my father having a 69 Chris Craft that was about 30 ft in length in 79. Not really any comparison compared to the 405 and I was 10. Lol
I probably bought more boat than I needed to start with or learn on.
Yes I am sure I got taken a few thousand by the repair shop in TX, however hindsight is 20/20. I have learned a lot and I do enjoy the boat when I use it. I simply need to use it more.

As always, thanks for your advice

[Erntster]

[quote="The pressure relief valve is a safety devise and your last defense if both the above fail or there is sudden high pressure in the system for a reason other than a runaway heating element, so I wouldn't mess with it. If it's leaking, replace it. If that's all that's leaking... When replacing the relief valve, make sure that you either use a Sealand replacement or one with the exact spec to maintain safety. Simply grabbing one off the shelf with the same size thread but completely different spec at your local hardware store is dangerous should something go wrong. ...[/quote]

Hi Viper,
I'm having the same issue with my P/T valve on my Seaward S1100 water heater. I definitely want to replace it with one matching specs of the existing. In search for those specs, Seaward => Whale => Attwood now? From the water heater manual:

"Pressure temperature relief valve is factory installed. The pressure relief shall limit the
pressure to 127.5 PSI (879.3 KPA) minimum, 150 PSI (1034.2 KPA) maximum."

The Seaward part #73127 is shown as the temperature/pressure valve for all models. Haven't been able to find that original part number, only replacements that "fit All Seaward Water Heaters."

O.K...all the replacements (Defender Marine #75794, for example) show Maximum of 100 PSI, whereas the manual spec calls for 127.5 psi minimum and 150 psi max.

If these are truly Seaward replacements, is a part designed for 100 PSI maximum going to present a problem when Mfg spec was 127.5 PSI minimum?

[Midnightsun]

If these are truly Seaward replacements, is a part designed for 100 PSI maximum going to present a problem when Mfg spec was 127.5 PSI minimum?

These valves open 2 ways, 1 is pressure and personally I would prefer it open at 100psi on a boating application as opposed to 125psi. Reason being is our water lines tend to run about 40-50 psi. I would not want 127psi on these lines as a failure would most likely happen on the line before the valve would get a chance to open, 100psi is much safer so yes this valve is even better IMHO.

The white probe that sticks out a few inches is a temperature probe which will typically cause the valve to open around 210F or just a hair below boiling point if you prefer.

[Erntster]

Perfect! Makes sense...I’ll start there.

Thanks Hans

[Viper]

Ya I agree with Hans. What you don't want to do is just grabbing something off the shelf and end up going the other way spec wise.

[Serendipity]

So here is the hot water heater update

If you own a 97 thru 2002 405 or 406. Then this should work for you.
So I received the new Whale S1100 11 gallon hot water heater from Hodges marine. This isn't a 30 minute job and would have taken me weeks regardless. I just need to know how things work, so I am methodical in how I repair stuff.
Aft cabin bed has to be completely disassembled I thought, but in hind sigh the bumpers may could have stayed on the bed probably.
So a marine hot water heater has a heat exchanger. I wasn't aware how this works, but I sure am now. Lol

You will also need a rear style hot water heat exchanger and they make a side and front version, so be careful here.
Fresh water holding tank has to come up and out to access the hot water heater. All hoses were stuck tight after 22 years. So I get the holding tank out and started working on the hot water heater.
Heat exchanger hoses are on the back side naturally. So I told myself, you need to get in the hole to look around and hook the hoses up naturally.
Yes at 6'4 and 195lbs, it wasn't designed for a man my size to get in there I surmise..
I liked to never got turned around and got my leg over the gas tank. No I didn't plan on going in, but I am the inquisitive type.
Once in I was going to remove the heat exchanger hoses while sitting directly in front of them. Who knew coolant would start spewing out once I took a hose off. lol,, So now I am in coolant:banghead:

I had a nice shirt on, so I removed it so my back could be right up next to the fiberglass. I really thought this out. Right guys lol

So once I was inside, I started shooting pictures. It appears my exhaust tubes have been resealed within the past few years. No water leaks noted. I could get to the trim tabs connectors pretty easily and the swim ladder bolts were secure.i am better for seeing what I could access myself inside. I am attaching pictures from the hole underneath the stairs.
So I put everything back together, double clampped all hoses and check for leaks. Tightened a couple hoses on the front and tested. No Leaks

I have the best water pressure ever since I purchased the boat and no air in the lines now, so the faucets don't spray or hiss. New hot water heater is a major plus

Hopefully ya enjoy my stories, because I try to paint them as they happen or as I live them.

Happy boating ya

[bud37]

Again thanks for posting....this will be a great help for those with the same type of task coming along...