505: Fresh Water System
Printed From: myHanse.com
Category: Hints & Tips
Forum Name: 505/508
Forum Description: 505/508 Hints, Tips and News
URL: https://www.myhanse.com/forum_posts.asp?TID=12922
Printed Date: 27 March 2026 at 01:44
Software Version: Web Wiz Forums 12.06 - https://www.webwizforums.com
Topic: 505: Fresh Water System
Posted By: SVZara
Subject: 505: Fresh Water System
Date Posted: 02 August 2021 at 23:02
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I have some questions for my understanding of how the two tank system works in the 505 (and possibly the 508). We have a forward tank under the master cabin bed that contains 450 liters and a tank under the settee on the starboard side that contains 180 liters. Both tanks feed a central water pump. Here are my questions and issues: 1) Which tank is #1, and which tank is #2 on the sensor panel? Our tank #2 empties first, then tank #1, just not sure which one is which? 2) Once tank #2 is empty and on 0%, tank #1, will get down to around 40% and then the water pump runs for a long time. I am not sure if it ever stops because I turn it off incase it could burn out. Why can't we access the last 40% of tank #1? That really cuts into our water availability. Is our sensor that far off or is this an indication of a problem in the water system? How do we get access to the entirety of our water capacity? Does this happen with the fuel tanks too? I would never run them dry but, how far can you really go down to? 20%? 10%? 3) Does Tank #2 gravity fill Tank #1 or are they totally separate? I assume separate cause they have two different fills, but I could be wrong. ------------- Marc S/V Zara 2016 Hanse 505, Hull #129 |
Replies:
Posted By: Arcadia
Date Posted: 02 August 2021 at 23:45
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I’m not familiar with the exact installation on the 505, but there should be valves on both water tanks and both fuel tanks. Usually near the tank outlet hose. It sounds like both valves may be open on your water tanks, and being at different levels, eventually you would start sucking air from the empty tank. You should defiantly check your fuel tanks if you have more than one as sucking air into your engine would a bigger problem, especially if motorsailing while heeled over. ------------- Leon / ARCADIA 2018 Hanse 588 Sag Harbor, NY |
Posted By: kipwrite
Date Posted: 03 August 2021 at 01:44
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On my 505 (#123), tank #1 is the larger one forward under the bed. #2 is the smaller one by the settee, starboard side. Both tanks have shut off valves - the forward tank's valve is port side, aft of the tank under the floor cutout. The smaller tank has a valve just forward near the bulkhead, under the seat. On my boat, if both tank valves are open, the smaller tank empties first and the valve then needs to be closed to avoid sucking air. The smaller tank will drain into the larger tank if both valves are open. Therefore, we open the tanks one at a time, keeping the other tank closed until it's ready to use. I replaced a faulty gauge on the forward tank and found it was several inches too short - it showed empty when it was still maybe 25% full. Pretty easy to find a proper length gauge, and they are easy to replace once you line up the screw holes properly. I know some owners have gone to better quality gauges, but the ones supplied by the factory have worked pretty well for me once they were the right sized. There is an inspection port in my water tanks that can be unscrewed. I'd have a look inside the big tank and see what's going on with the pickup. But my suspicion is that if you close the valve on the smaller (now empty) tank you will be able to access the rest of the water in the larger tank without sucking air. Hope this helps.
------------- Kipwrite |
Posted By: SVZara
Date Posted: 03 August 2021 at 03:44
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Thank you. This is exactly what I needed to know. I will try closing the valve on the smaller tank once its at 0% and see how it goes from there with the larger tank. I mistakenly thought the freshwater system would automatically manage this. I will also take note of the tank levels when they get to 0% and see if they are truly empty. ------------- Marc S/V Zara 2016 Hanse 505, Hull #129 |
Posted By: ohthetrees
Date Posted: 03 August 2021 at 04:57
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kipwrite had it exactly right, I just have a couple of things to add. If you have both water tank valves open, water can move back-and-forth between the tanks confusing issues. On our boat we have a policy that we never have both tanks open at once. We typically run on tank 1 (forward tank) and keep the aft tank as reserve. When the forward #1 tank reads 0%, we know that we have used about half (!) of the water that is really in the forward tank. We keep using the forward tank until it is empty which we know when the water pump runs freely. If we are on passage or far from possible refill, we take note of the exact water level in tank 1 by lifting the floor panel and looking with a flashlight for the waterline in the translucent tank. To transfer tanks we close both tank valves, then open the valve to tank 2. We have a policy of never having both tank valves open at the same time so water doesn’t run back-and-forth between tanks. One other quirk, if you are healed over on a port tack, you only have access to half the water in the forward tank. In that circumstance the gauge actually reads pretty accurately!
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Posted By: SVZara
Date Posted: 05 August 2021 at 01:34
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Has anyone considered a solenoid valve attached to the sensor and have it shut on its own when the tank is empty? For some reason, I had assumed the boat had this already. Any reason I wouldn't want to do this?
Is there a way to recalibrate the water level sensor? For example, if the tank says 0% and actually has 2" left in the tank, I would like to adjust the sensor to get it correct. ------------- Marc S/V Zara 2016 Hanse 505, Hull #129 |
Posted By: Fendant
Date Posted: 05 August 2021 at 11:15
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Marc, the problem with the reliable magnetic sensors is, that they only come in fixed lengtha ( 50 mm steps ). You might have a tank with a depth of 480 mm, so your sensor is 450 mm, its hows enpty when you have still 6.5% of the tank volume left. , thats nearly 20 ltr in a 300 lts tank. The only solution would be to fabricate a adapter flange which is 20 mm hicker ( if you have enough space above the tank  ).AFAIK Philippi Germany might make them according to your tank depth, don't know the costs. ------------- Frank |