Hatteras 42 LRC replacement water heater help, specific to the 42 LRC

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Rays53hatt

Rays53hatt

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Aug 11, 2024
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I have a 42 foot Hatteras LRC that has a rusted and dead water heater. Cold water nipple broke off because of corrosion.
Does anyone have experience removing and replacing this water heater in this boat? The space between the Starboard DD and the genset is too narrow to allow the heater to pass. I can saws all the old one to pieces and remove it. However, to install a new one, it looks as though I will need to remove the frame of the Gen Set and then start removing parts of the DD until there is space for the new one to pass. The other option is installing a 110 on demand heater. I know the consciences is that this is a bad idea because of the power suck. We have done some measuring with buckets and a stopwatch in the shower, and we will use about 10 gal of hot water a day. So, the power suck isn't so pronounced for us.

Q1: Am I wrong about what it's going to take to make the space to get a new one in?

Q2: Anyone using a high efficiency 110 on demand water heater that they like?


Regarding the on-demand heater. Our water pressure provides just under a gallon of hot water a minute. So, the small units that go under a residential sink will suffice. As long as two people don't try to shower at the same time.

Assuming I do all the work.
Cost of replacement with what is comparable with original is going to be $800-$1200
Cost of a 1.4 gal per minute on demand heater is $190 - $250

I am going to post another thread with formulas and calculations about on demand vs traditional tanks for all the geeks who want to chime in.

This thread is just, anyone removed and reinstalled a water heater in a 42 LRC and anyone with a 110 water heater they like
 
I have only been on a 42 LRC once about 20 years ago so I am not familiar with the boat very much. How about cutting the deck above the water heater and taking it out that way?
 
Rays53hatt said:
I can saws all the old one to pieces and remove it. However, to install a new one, it looks as though I will need to remove the frame of the Gen Set and then start removing parts of the DD until there is space for the new one to pass.
Click to expand...

Our original water heater is leaking, replacement ordered...

Different boats, of course, but we would have had a similar problem if we replaced the original with a similar sized/shaped model.

Instead, I shopped the whole market of water heaters, found one shaped differently, and I think I can get the new one in... intact... without removing engine bits or raw water intake strainers/hoses.

In our case, that meant the new one will be a horizontal tube shape, from Torrid. (Versus a cube, of sorts.) I used an inflatable fender, slightly larger, to test moving through the engine room without dismantling stuff... seems to be workable.

-Chris
 
Our 42LRC has the water heater in the lazarette. I am unsure whether it was installed there by the PO, but tbh, I think that was original (but 1977!)

Our genset is just infront of the starboard DD (original install for sure)
 
ranger58sb said:
Our original water heater is leaking, replacement ordered...

Different boats, of course, but we would have had a similar problem if we replaced the original with a similar sized/shaped model.

Instead, I shopped the whole market of water heaters, found one shaped differently, and I think I can get the new one in... intact... without removing engine bits or raw water intake strainers/hoses.

In our case, that meant the new one will be a horizontal tube shape, from Torrid. (Versus a cube, of sorts.) I used an inflatable fender, slightly larger, to test moving through the engine room without dismantling stuff... seems to be workable.

-Chris
Click to expand...
Chris, that’s a great idea. What model number did you choose? I will look into the torrid brand. Did you have to size all the old one out?
 
Variemeh said:
Our 42LRC has the water heater in the lazarette. I am unsure whether it was installed there by the PO, but tbh, I think that was original (but 1977!)

Our genset is just infront of the starboard DD (original install for sure)
Click to expand...
My genset is between the two shafts, centered between the Detroits at the aft end of the engine room. The water heater is to the starboard side. so it will need to squeeze between the generator and the back end of the Detroit and the ceiling.
 
Rays53hatt said:
I have a 42 foot Hatteras LRC that has a rusted and dead water heater. Cold water nipple broke off because of corrosion.
Does anyone have experience removing and replacing this water heater in this boat? The space between the Starboard DD and the genset is too narrow to allow the heater to pass. I can saws all the old one to pieces and remove it. However, to install a new one, it looks as though I will need to remove the frame of the Gen Set and then start removing parts of the DD until there is space for the new one to pass. The other option is installing a 110 on demand heater. I know the consciences is that this is a bad idea because of the power suck. We have done some measuring with buckets and a stopwatch in the shower, and we will use about 10 gal of hot water a day. So, the power suck isn't so pronounced for us.

Q1: Am I wrong about what it's going to take to make the space to get a new one in?

Q2: Anyone using a high efficiency 110 on demand water heater that they like?


Regarding the on-demand heater. Our water pressure provides just under a gallon of hot water a minute. So, the small units that go under a residential sink will suffice. As long as two people don't try to shower at the same time.

Assuming I do all the work.
Cost of replacement with what is comparable with original is going to be $800-$1200
Cost of a 1.4 gal per minute on demand heater is $190 - $250

I am going to post another thread with formulas and calculations about on demand vs traditional tanks for all the geeks who want to chime in.

This thread is just, anyone removed and reinstalled a water heater in a 42 LRC and anyone with a 110 water heater they like
Click to expand...
So I bought a whale 4 gallon 110 volt water heater. It's technically not instant in the winter time I have hot water in about 7 minutes in the summer how about 5 minutes.
 
Rays53hatt said:
Chris, that’s a great idea. What model number did you choose? I will look into the torrid brand. Did you have to size all the old one out?
Click to expand...

MHS 17 IX. Hasn't arrived yet, and we haven't started removing the original Atwood 20 (actually 17.9G) yet either, still slogging along with that.

-Chris
 
Rays53hatt said:
Chris, that’s a great idea. What model number did you choose? I will look into the torrid brand. Did you have to size all the old one out?
Click to expand...
I have had two Torrid water heaters, both gave good service. The last one, 20 gallons, has two heat exchangers: One connected to the stbd engine and the other to the hydronic heating system. The tank on my boat is forward of the stbd engine and wasn't easy to change but doable.
 
Rays53hatt said:
My genset is between the two shafts, centered between the Detroits at the aft end of the engine room. The water heater is to the starboard side. so it will need to squeeze between the generator and the back end of the Detroit and the ceiling.
Click to expand...
Ours in on the port side behind the main engine. Odd that our hull #428 is different.
A water heater is next on my to-do list but not because it's not working but because we want it to be engine-fired through a heat exchanger. I havent started the removal yet but eyeballing it doesn't raise any red flag issues...I know I'll need to remove the fresh water pump thats under the stairs leading down to the aft stateroom between the heater and the generator and probably the raw water pump and plumbing to open up access behind the main. I did the same disassembly thing to gain (easier) assess to behind the starboard main ,too, so as to be able to remove the port 8-D battery outboard of the engine (what a huge pita). I removed vacuflush system (which I did away with) that was sitting on the shelf where you say your water heater is. I also removed the starboard raw water pump and hoses, the shift cables & bracket from the clutch and the throttle cable to give me room to get myself in there and the equipment out. Maybe that's all you need to do is pull some bolted on stuff off of the main to gain more room to slide the heater out.
 
Rays, I must adamantly disagree with your statement. Two people can absolutely shower at the same time & use no more water !
 
Rays53hatt said:
I have a 42 foot Hatteras LRC that has a rusted and dead water heater. Cold water nipple broke off because of corrosion.
Does anyone have experience removing and replacing this water heater in this boat? The space between the Starboard DD and the genset is too narrow to allow the heater to pass. I can saws all the old one to pieces and remove it. However, to install a new one, it looks as though I will need to remove the frame of the Gen Set and then start removing parts of the DD until there is space for the new one to pass. The other option is installing a 110 on demand heater. I know the consciences is that this is a bad idea because of the power suck. We have done some measuring with buckets and a stopwatch in the shower, and we will use about 10 gal of hot water a day. So, the power suck isn't so pronounced for us.

Q1: Am I wrong about what it's going to take to make the space to get a new one in?

Q2: Anyone using a high efficiency 110 on demand water heater that they like?


Regarding the on-demand heater. Our water pressure provides just under a gallon of hot water a minute. So, the small units that go under a residential sink will suffice. As long as two people don't try to shower at the same time.

Assuming I do all the work.
Cost of replacement with what is comparable with original is going to be $800-$1200
Cost of a 1.4 gal per minute on demand heater is $190 - $250

I am going to post another thread with formulas and calculations about on demand vs traditional tanks for all the geeks who want to chime in.

This thread is just, anyone removed and reinstalled a water heater in a 42 LRC and anyone with a 110 water heater they like
Click to expand...
Hi !

I have Hull 322 built in 1978 and the genset is in the engine room on the starboard side between engine and forward cabin bulkhead. My water heater is in the lazarette ! I am doing a huge refit in Europe. Any question... do not hesitate.
 
We have a 42 LRC mark II, we replaced our hot water heater while on the loop last year. The same thing, went sightseeing in Savanna and returned to a steamy engine room, the lower heating element had rusted out. I was able too snake the old 20 gallon tank out behind the starboard engine by removing exhaust and water hoses. I couldn’t find a similar sized tank so replaced it with a 6 gallon tank that has worked well and no water supply issues for showers 🙃
 
My water heater on my 42 LRC is also in the Lazarette on the starboard side.
 
I installed a traditional, big square box stainless steel 11 gallons. I had to take parts of the Detroit diesel apart to get past the water intake and several cables. But ended up being OK.

I was determined to use on-demand water heaters. The problem is my solar system has 1200 amp hours, but only 3000 W. I would have to add a second inverter so that I can get to 6000 W to run anything that seems to be powerful enough to do what I need to do. The ones that you suggested are 2000 W. I could install one of those but not 2
 
As I pointed out in your other thread, 120V on demand is not feasible. Notwithstanding the detailed calculations you went through, you are missing the key component in this scenario; flowrate. You have calculated how much power is required to raise how much water to what temp. What you are missing is how fast. That whole equation gets much more complicated quickly, but this is the easiest way to look at it. Google on-demand water heaters, and pick a small one, say 1.5 gpm. Look at the specs and you’ll find it will have something like a 35,000 BTU burner (it will be gas/propane). That will give you a good practical idea of what is required to reasonably drive this device in the real world.

So 35,000 btu of heat requirement translates to 6730 watts of electric @ 120VAC. 6730 watts on a 120V circuit is 56A of current. Not. (And just for fun, using your solar comments. That is 600A @ 12V, including a bit for inverter efficiency.)
 
Rays53hatt said:
I have a 42 foot Hatteras LRC that has a rusted and dead water heater. Cold water nipple broke off because of corrosion.
Does anyone have experience removing and replacing this water heater in this boat? The space between the Starboard DD and the genset is too narrow to allow the heater to pass. I can saws all the old one to pieces and remove it. However, to install a new one, it looks as though I will need to remove the frame of the Gen Set and then start removing parts of the DD until there is space for the new one to pass. The other option is installing a 110 on demand heater. I know the consciences is that this is a bad idea because of the power suck. We have done some measuring with buckets and a stopwatch in the shower, and we will use about 10 gal of hot water a day. So, the power suck isn't so pronounced for us.

Q1: Am I wrong about what it's going to take to make the space to get a new one in?

Q2: Anyone using a high efficiency 110 on demand water heater that they like?


Regarding the on-demand heater. Our water pressure provides just under a gallon of hot water a minute. So, the small units that go under a residential sink will suffice. As long as two people don't try to shower at the same time.

Assuming I do all the work.
Cost of replacement with what is comparable with original is going to be $800-$1200
Cost of a 1.4 gal per minute on demand heater is $190 - $250

I am going to post another thread with formulas and calculations about on demand vs traditional tanks for all the geeks who want to chime in.

This thread is just, anyone removed and reinstalled a water heater in a 42 LRC and anyone with a 110 water heater they like
Click to expand...
I’m new here but I replaced my 10gal water heater on my 1982 42LRC a couple years ago. It sat in a cradle just starboard of the gen set which sits between but aft of the Detroits
 
I just replaced the 20-gallon water heater on our Carver Voyager 530, I had the same issue as you, not enough clearance to get the old one out and a new one of the same capacity back in. After a little studying, I cut an access panel in the washer / dryer compartment which is directly next to the water heater and was able to make the swap. The water heater is next to the bulkhead in front of the starboard engine- the red arrow is pointing at the W/H in the photo below,
 

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What's up with all these 20-gal water heaters? I recently went from an 11-gal traditional cylinder marine heater to a 20-liter (5-gal) water heater that has better insulation and works fine.


There is also a slim model

Granted I'm in temperate climates these days, but water line distances on boats are pretty short and the water heaters well insulated.

Do you really need a 20-gal water heater, or is it that's what came out so putting same back in? Most boats don't carry enough water to be profligate with usage. What's up?

Peter
 
mvweebles said:
What's up with all these 20-gal water heaters? I recently went from an 11-gal traditional cylinder marine heater to a 20-liter (5-gal) water heater that has better insulation and works fine.

Do you really need a 20-gal water heater, or is it that's what came out so putting same back in? Most boats don't carry enough water to be profligate with usage. What's up?
Click to expand...

Ours came with a "20" -- actually 17.9 -- so I'm replacing with a 17. Mostly aiming to replace like (capacity) for like. I'm expecting to need a Sawz-All or angle grinder to get the old one out, sometime over this winter. As it happens, the replacement is a different shape, hopefully easier to get it into place.

Can't say we've particularly challenged our hot water capacity, but if we ever had a full boat and folks showered sequentially we'd probably be right on the edge...

-Chris
 
mvweebles said:
What's up with all these 20-gal water heaters? I recently went from an 11-gal traditional cylinder marine heater to a 20-liter (5-gal) water heater that has better insulation and works fine.


There is also a slim model

Granted I'm in temperate climates these days, but water line distances on boats are pretty short and the water heaters well insulated.

Do you really need a 20-gal water heater, or is it that's what came out so putting same back in? Most boats don't carry enough water to be profligate with usage. What's up?

Peter
Click to expand...
We have a Carver Voyager 530 Pilothouse- two heads and showers, and we carry 200 gallons of fresh water. We stay on the boat frequently and use the showers daily. We do not walk up to the marina heads to shower. 20 gallons of hot water is enough for us to live "normally" when on the boat- we do connect to dock water when in our slip and of course change our habits a little when at anchor.
 
ranger58sb said:
Ours came with a "20" -- actually 17.9 -- so I'm replacing with a 17. Mostly aiming to replace like (capacity) for like. I'm expecting to need a Sawz-All or angle grinder to get the old one out, sometime over this winter. As it happens, the replacement is a different shape, hopefully easier to get it into place.

Can't say we've particularly challenged our hot water capacity, but if we ever had a full boat and folks showered sequentially we'd probably be right on the edge...

-Chris
Click to expand...
I decided to remove the old water heater whole, cutting up the old unit in the engine room would have created a huge mess and long-term rust spots everywhere a grinding landed while cutting up the old one. Cutting the access panel did create a bit of saw dust, but I was able to contain most of it with a shop vac and a few drop cloths.
 
To make life interesting all boats are built differently. When we bought our ex hireboat Broom 42 flybridge boat it had a s/steel badly insulated horizontal calorifier tank which couldn't hold any heat overnight, when I get up I love to shave and shower in hot water (military training)..
We removed it, cut it in half, fitted it with a leg frame, a handle and hinges and it became the marina BBQ.
Back on subject, we searched first of all how we could increase the space, we removed half of the saloon seating/floor. Two horizontal braces were removed and redesigned to retain the hull strength. Then we were able to fit a fully insulated with expanded polyurethane 75 litre horizontal single coil calorifier tank, the top of the tank is level with the top of the engine so there is no heat loss through thermal convection. The tank is heated by the engine when cruising and a 1Kw electric heating element. A hot/cold mixer valve is fitted on the water outlet to regulate the domestic water temperature to 65'C (above 60'C eliminates the possibility of legionaires disease) and conserve heat, for safety, the mixer valve also stops the admiral getting scalded with hot water when cruising. The calorifier is perfectly capable of supplying enough hot water for our fitted bath (great for old sailors aching muscles).
We fitted a small hatch to access the thermostat should we need to regulate the temperature.
After fitting we rebuilt the saloon back together with a few more modifications to make life easier in future.
Before you commit to any model first ascertain the maximum space you can make available because once fitted correctly it won't need to come out again for about 25 years. Its not an easy task but the long term benefits far exceed the hassle.
Check out the following websites, in the UK ASAP supplies, Beccles and SVB24 marine supplies Germany. Both companies ship around the world and remember !
Quality is remembered long after price is forgotten.
 
Last edited:
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