Roger & Marie

Voltage checks are useful but don't really indicate the health of a battery accurately. As long as the batteries are not fully sealed then the best testing method is to measure the electrolyte specific gravity (S.G.) with a hydrometer. The electrolyte is the dilute acid in each of the six cells that comprise a 12V battery. If each cell is in good health and fully charged then the S.G. should be around 1.260 but if the cell is fully discharged then this can be down to around 1.120. Unfortunately, it only takes one bad cell in a battery for the whole battery to be useless. If the a 12V battery has six caps on the top then these can easily be removed for testing although sometimes they are covered by a single long strip. However, if these caps cannot be accessed or removed then the battery is fully sealed and no S.G. testing is possible. Note that these same caps can also be used to top-up a cell with distilled water if the electrolyte level is too low - it should just cover the top of the internal plates. This is a link to a typical battery hydrometer This is a link showing how to use a battery hydrometer

Well, we have just come back from a week aboard "Broad Oak" on the Lancaster Canal (I know, I know!) and had a great time despite the lack of locks. As a party of wrinklies this just suited us fine! Re my original question, I wanted to feedback that we did take a wireless doorbell with us and it worked with great success, being clearly audible positioned at the front of the boat when triggered from anywhere around the back of the boat. I modified the bell push by attaching an old camera strap and so I could keep it around my neck for immediate use if crew attention was required. If anyone is interested we used a cheap SilverCrest unit from Lidl, Model No. Z32155, IAN 60113. http://www.lidl-service.com/cps/rde/xchg/SID-383690CB-0319DE44/lsp/hs.xsl/product.html?id=89379162 So, thank you to everyone for the interesting responses and, in particular, to koukouvagia for the wireless doorbell suggestion.

Thanks for all the helpful replies, folks. It looks like the walkie-talkies should work and so we will keep an eye out for a set at a good price. As we intend hiring a boat, a wired intercom is not really suitable unfortunately. However, the wireless doorbell is an option as we already have one and wondered if this would work on a steel boat - so thanks for confirming this. Unfortunately, I think the boat is too long for voice-power alone, even with the aid of a megaphone. We wondered about using the horn but thought this might be a bit anti-social so wanted something a bit less intrusive. Anyway, thanks for everything so far. It would be good to hear from anyone else with experience of using wireless doorbells on steel boats.

Newbie on these forums and with very limited narrowboat experience from many years ago but tempted back shortly for a holiday. For medical reasons, we now need reliable communication between the "steerer" at the back and the "crew" in the front, both when inside and outside the cabin. I know that some boaters use PMR 446 Walkie Talkies between the boat and the towpath but can anyone confirm that these also work reliably onboard a steel narrowboat as I have described? I am particularly concerned that the steel structure may shield the signal in places, making radio communications unreliable.