Technical
Page
Page updated:
19th Dec 07

This technical page has been called the Chat room for quite some time now, Chat room being a euphemism for us chatting to you. Yes its a bit one sided but how else do we get our point across. And do be aware that everything below does represent the view of the author/editor.

Chat Room Topics

  1. Bicycles - choices, wheel size, folders, gears, suspension, comfort,  web sites.
  2. Communications - Mobile phones, SIM cards, phone cards, WiFi, internet, Skype, HF radio.
  3. Gas - Propane or Butane, bottles, refilling and transferring.
  4. Health and Fitness - life style, diets, exercise.
  5. Shade - from sun and rain.
  6. Toilets - why pipes fur up, holding tanks.

and click here for the new Cruising Tips Page,    and here for the  Software download page


Janet cycling thro' Frinton 2004.
Janet cycling thro' Frinton 2004.

Bicycles on board

Bicycles, love them or hate them, useful or a waste of time and space; much has been said about them so what is best?  They don�t suit everyone hence the conflicting reports of their desirability and usefulness. But do be aware I have strong views on bicycles so read on with caution.

If you have sailed away from your homeport you will obviously be without land transport other than shanks� ponies, and if the time away is short then they will suffice, but for longer stays away then what? Transport is really only needed for provisioning trips to the local markets and super markets, carrying diesel from garages, and for site seeing beyond the immediate area of the mooring. And it�s on prolonged holidays and longer journeys when all of these seem to occur. From the title then you will see I�ve ruled out public transport and chosen bicycles as the solution to our daily transport needs.

Others have similarly chosen to take bicycles on board and also found them a real joy, whilst some have hated them and the space they consume. I learn that those who value them willingly allocate prime space irrespective of how big they are, whilst those who see them as lacking in some respect curse every inch of space lost to them even if they are the smallest of folding bicycles.

Ideally, and this I must stress is but a dream, the boat will have space for 2 full size mixed-terrain-bicycles with front and rear suspension, or mountain-bikes but with those horrible energy sapping knobbly tires replaced with something smoother and able to be inflated hard, really hard if any road or surfaced paths are to be contemplated. But lets get real again, how many have room for such things, so what then, a folding bike? Yes a folding bike but not any folding bike.

For a bike to be any good the rider must feel comfortable on it but sadly, however, the bike is normally blamed even when it is the rider who is at fault and here is the difficulty, how to get a non-discerning would-be cyclist to make a real value judgment when its likely he or she will be ill at ease on almost anything. First step then, learn to ride a bike before buying one. Try your kid�s bike (or is that grand kids bike?) and learn to ride 10km on it. If you constantly fail to make the distance then its still 80% likely its not the basic bike which is at fault. I�m assuming here that it�s an adult�s bike, with smooth rock-hard tyres and a saddle so high that you can only just reach the floor. Surprised at the last point, well don�t be, its where most go wrong; a low saddle equals aching legs. The saddle height needs adjusting so that the leg is only slightly bent with the pedal at the bottom; this means touching the floor might be a real stretch. After all, you need to be efficient when cycling not when standing still or posing at home in the driveway. Style gets you no points if you need to push the �accursed contraption� as your legs are wrecked 5km from home. So having learned to ride what bike to get?

I think we�ve agreed it will be a folding bike but which one; a sub £100 from some mail order company or a £1000+ from the US, or maybe something really exotic like a £4000 titanium Moulton based on an original idea by Sir Alec Issigonis (he did the original Mini as well). In all of these examples you largely get what you pay for so if you want to spend circa £100 then get yourself a good set or training shoes and stick to walking, beyond that use the following to aid your decision.

Wheels � the bigger the better. You�ll initially feel more stable and they ride the bumps better. Folding them is difficult though! Ours are 16 inch so don't need folding.

Gears � derailleur gears are too fussy and hang very low on small wheel bikes so making them prone to impacts when riding off-road, but for performance they are the ultimate, alternatively get hub gears. I criticised hub gears for years when I raced bicycles but now find them to be a perfect fit with a live-aboards needs. I have a 3 speed hub and Janet has an older 5 speed version, of which I am most envious; since Sturmey-Archer went out of business (or was it bought out by the Chinese?) the latter has become unavailable. Shimano do a 7 speed hub but getting a wheel built with one is difficult due the spoke number and anyway it is likely to cost more for the hub than most spend on the whole bike.

Suspension � really helps with small wheels. We have it only on the rear and so have soft handlebar grips to try soften the front, we should use gel gloves as well when riding off-road. It�s a very low cost and low weight solution though.

Saddle - Ladies, get a ladies saddle perhaps with a hole in the middle so as to not put pressure on delicate areas. A gel filled saddle helps too. Gents avoid the razor thin ones unless you have a background of 150 miles in the saddle per day. I also like the hole in the middle as it takes pressure off sensitive areas on us blokes too. �nufff said.

Frame � titanium is the ultimate, its light and corrosion resistant but cost mostly precludes it; aluminium is next best though not for racers where it�s a bit rigid so gives a hard ride but for live-aboards it is light and very corrosion resistant. Stainless is usually costly and designed to overwhelm you with its apparent quality but it�s the use of �what�s available� tube sizes which makes it heavy and also the fact its made by companies you have never heard of and who rarely know anything about bikes. Oh and by-the-way its not usually the frame which corrodes on a steel bike.

Comfort � usually this is down to the overall design, but it the real world it might be that folded size is more important to a company, from a marketing stance, than rider comfort so do try riding one for at least 10km before you buy (this might mean using a friends). I've found a direct correlation between unhappy owners and crap designs. One obvious area is wheel base; some have such a short one they almost pitch-pole under braking or buck the rider off the back on a hill. The bike needs to be long enough such that the rider leans slightly forwards and so becomes part of the ensemble.

Where to buy � try the internet. Decide what you want then find a web site specialising in that model or in folding bikes in general and seek a second-hand model. Usually you�ll find that for half price you�ll get an as-new example, probably having the entire extras list for free. I know we did, and times two although it took 6 months. Caution though; if you look for cheap crap you'll certainly find it, and pay dearly for it so stick to good makes; remember its quality you're looking for and at a knock down price.

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Communications

Maintaining contact with home, either needs a mobile phone with a local SIM card, a local phone card or an internet connection.  Using any of these will give a least cost solution. 

Phone cards, available at supermarkets and tobacconists, mean a saving of up to 50% when making an over seas call.  They are of little use for incoming calls.

Choosing a mobile phone. Any mobile phone made in the last 4 years will be at least "Dual band" so will work on all non-US networks (Korea has also adopted the US standard).  If travel to the US is planned then a "tri-band phone" i.e. one additionally covering the US 1900 MHz band will be needed.  Additionally, and this is key, the phone must be unlocked or unblocked (depends on terminology) so as to work with all SIM's and on networks beyond the UK shores (try a friends SIM from another network as a check).

Of late I see more areas covered by GSM than I do covered by trees or grass, GSM is that ubiquitous, and so offers an excellent means for making calls to, and receiving calls from home; cost is an issue though. Here in France my UK Virgin mobile SIM means I pay £0.60/min to make a call and £0.30/m to receive a call whereas a local bought SIM (I randomly chose Orange) means receiving an overseas call costs the same as a local call and making a call to UK is £0.20/min cheap rate. The only down side is that UK callers now need to make an overseas call to reach us but with the BT's "friends and family" the cost is much reduced. And when sailing off-shore GSM can often be received up to 30Km out to sea, that's if the local network has chosen to point an aerial that way, but its something not to be relied upon.

GPRS, and the soon to be popular EDGE, also have the same propagation characteristics as GSM as they use the same frequencies and the same base stations, so from a data perspective they will soon have the same area coverage. This means that weather services, graphic rich displays, moving video clips, and every thing the wallet can support will be available up to 30 Km off-shore. And after EDGE comes 3G, but will my pension support it? 

And for those in the know . . . . " if EDGE is a success who'll need 3G,  and if its not why bother with 3G ". One to watch folks.

Internet voice calls are quite new to me but seem pretty good, and at £0.01 per minute (one penny per minute) are really cheap. All you need is an internet connection and the free software from Skipe loaded and running on your lap top. Its difficult so say anything more other than, er yes, an internet connection is needed. Marinas now seem to be offering a WiFi connection to those with radio enabled laptops.  

WiFi is a recent addition to almost all laptops and as you travel around you might see signs saying "WiFi Hotspot" meaning you have access to the internet in this area, initially it was at airports and train stations but now most towns, even villages, have an internet cafe which offers WiFi connection to the internet and, more importantly, many marinas offer the facility. So, before you sail away become familiar with WiFi, particularly changing passwords, changing networks, selecting a network, finding what networks are available. Your grandson will know all about it, ask him to show you. I would also advise you to get a WiFi solution which resides outside of the computer.

For older laptops you will have to have an external WiFi solution for connecting to the USB port on the PC. Cheap WiFi units come in the form of a little blob 50 mm long with a USB connector at one end, they cost about 20 Euros, so not expensive but my recommendation is to avoid these and go for something which is likely to pull in signals from the internet cafe 200m away.

During October 2007 I surveyed as many specs for WiFi product as I could find on the internet. I mainly looked at receiver sensitivity, receiver noise figures and transmit power. Also I only considered units which supported an external aerial. I disregarded the new 802.11n standard as being an unnecessary complication. 802.11g at 54 Mbps is fast enough, and anyway that's only the radio link not the bandwidth that the internet connection will allow you. The cafe might have only an 8 Mbps broadband connection and that's likely to be shared across 16 users so about half a meg each. In tests I see most times that's the figure I'm actually working at. At the end of the survey I purchased a Senao EnGenius 362Ext supporting 802.11b/g. I also needed an aerial.

The unit came with a 2dBi antenna and most times in marinas this is fine but for better overall performance something like 9 to 12 dBi is a really worthwhile improvement. These can be for outside use or inside use. The former is more costly and most of that cost is the housings weather proofing. I chose an internal one at 11 dBi and its a directional aerial. Being directional it needs pointing at the source and so likely to complicate internet surfing whilst swinging at anchor. Up side though, my aerial was 9 Euros, an external omni might cost 100 Euros.
If any of this fails to make sense, email me with your query or ask your grandson.

SSB on the HF Radio bands,  is a quite an elderly form of communication, in fact my dad started using it in 1936 as a radio amateur with the call sign G8PK. Today, as a means of voice comm's, it differs little to that of 1936 (and I still use dad's call sign but now G8PK/MM) but what has changed is its use as a vehicle to transport data, and data is what will interest most. Data, in the form of weather information, via TTY or fax, is available world wide on the HF radio bands using SSB receivers and laptop PC's.

On Ruby, and previously on Mithril, we have an ICOM IC-706 HF/VHF transceiver but for downloads any good SSB receiver will probably do, remembering of course that the installation techniques contribute as much to receive quality as does the actual receiver. So get a good aerial (that's an antenna for those who don't speak English) and a good ground connection (er sea water connection probably); also don't share power supply leads with other pieces of electronic equipment as these invariably produce lots of interference, and the best way to fall foul of it is by sharing power leads.

Software for the laptop is available from the internet.  We use SeaTTY because the more frequently used JV-Com did not support my PC's soundcard. I've used JV-Com before and its a great product but since trying SeaTTY I'm a convert to it.  So much so I've upgraded to the full version for $29.

click to see a small excert from the Atlantic chart'

As for TTY, DWD Hamburg gives super coverage in the Baltic and Mediterranean but for the Atlantic and Biscay, although the signal is equally good, the information is poor. Frequencies used are, 147.3 kHz, 11039 kHz, 14467.3 kHz, 4583kHz, 7646 kHz, 10100.8 kHz. Weather fax are available from Fleet Weather and Oceanographic Centre Northwood England on 2618.5 kHz, 4610 kHz, 8040 kHz and 11086.5 kHz.

The downside to both TTY and Fax is that the data rate is very slow, i.e.4800 baud, so that it takes about 3 hours for the transmissions to cycle round all of the pages; some pages are only repeated every 6 hours and, naturally, the one you really want is on a 12 hour cycle. The upside is that the received quality is good, the content is recent and as accurate as weather forecasts can be, and its all free.

Email via SSB. This is something I'm currently moving towards, but only slowly as we seem to get good WiFi of late. It comes in two flavours, a) as a radio amateur using Airmail and, b) as a paying customer using SailMail.

Both need a rather expensive modem called a Pactor modem (versions 1,2 or 3) and the SW to run on it and, obviously, a transceiver as 2 way communications are needed. (Note: a new software development called SCAMP is soon to become commercially available and it will replace the Pactor modem - comments now added below) Both are restricted to text, and file sizes are limited but for run-of-the-mill emails it sounds great. We have friends using it and they swear by it. Also it does seem quite a polished product over all; not quite plug and play but once set up its almost automatic.

AirMail is "email for the airwaves", a radio messaging program for ham, SailMail and other licensed radio systems. AirMail offers an easy email-style user interface, and was especially designed for the SCS PTC-II DSP multimode Pactor-2 controller (phew!). Airmail also supports most other Pactor modems. Airmail also includes some features for retrieving messages when an internet connection is available, for example WinLink 2000 and Sailmail's POP server.

Airmail is not "freeware" and is not "public domain". software. License to use it is granted only under the certain terms but Airmail may be freely used without charge on amateur radio bands by licensed hams.

The SailMail Association is a non-profit association of yacht owners that operates and maintains a network of private coast stations in the Maritime Mobile Radio Service. The Association provides radio-printer (e.g. Internet email) communications for its members on a cooperative basis, in order to meet the private business and operational needs of the members' yachts. The SailMail Association provides worldwide coverage through the operation of 15 stations in North America, Hawaii, Australia, Southeast Asia, South Africa and Europe. Sailmail costs $250 per annum but can be used for business purposes.

Winlink-2000 (WL2K) is a new ham-radio mbo system introduced in late 1999 by Hans Kessler N8PGR, Vic Poor W5SMM, Rick Meuthing KN6KB and Steve Waterman K4CJX. WL2K is fully integrated with the Internet, and uses Internet message forwarding to make user messages available at any station which they normally connect with.

SCAMP - a software replacement to the Pactor modem.  The developer Rick KN6KB says, (this is the techy bit, and its a quote)

I am calling the new mechanism SCAMP (Sound Card Amateur Message Protocol). It is a pipelined asynchronous ARQ mode targeted at BBS to BBS or file transfer (not casual keyboarding). It will probably run throughput somewhere between Pactor II and III but uses a 2 KHz bandwidth. Currently using standard sound card and sound card interfaces (e.g. Rig Blaster). Barry is working on the next version of RDFT which will give more throughput. The protocol is currently integrated into the client program Paclink for my on-air testing.

We are currently running initial on-air tests over a 500 mile HF path which look encouraging. When released it should allow two Paclink stations to exchange email (with attachments) using just a sound card, sound card interface and Radio (FM or SSB). If tests come out encouraging it may be integrated with Winlink 2000 as an alternative mode to Pactor (lower cost to the user). Info on the current version of Paclink is available at www.winlink.org/client.htm but the download on the site DOES NOT yet contain the SCAMP protocol.

There is no free lunch however....this involves lots of CPU and DSP computing and will probably require a 1 GHz Pentium to run at max speed. My software will currently run with slower machines (since it is Asynchronous ARQ) but throughput will degrade. But as we know computer horsepower is not too expensive and keeps getting better and cheaper.

For more detail, as this is only a top level view, see the web sites below.

Communication web sites

  • Skype Low cost calls via the internet.
  • ICOM pretty good kit. We have an old IC-706, it's great.
  • Ham operator a good place to start.
  • RTTY, Weatherfax etc
    • JV-Com another great package but it didn't support my sound card.
    • MMTTY if you want to transmit as well.
    • DWD schedule covers the English and German language RTTY broadcasts.
    • Fleet Weather Center schedule covering the weather fax broadcasts from Northwood.
    • AirMail a free route for licensed amateurs to have email (not for business use).
    • WinLink 2000 Airmail via the internet.
    • SailMail as AirMail but for yotty's to have email aboard and it can be used for business.
  • RSGB Radio Society of Great Britain.
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Gas - propane and butane etc

Gas in hot water bucket.
Gas in hot water bucket.

On some pontoon in every port someone is worrying about gas, and probably right now.  I know this because in La Rochelle its me (21st Nov 05). The temperature has fallen and the butane pressure is now quite low so, as you can see, I've popped the bottle in a bucket of hot water. But looking at the bigger picture then; what sort of gas, which bottles, will the cooker be happy, etc, etc, this is what we must all face as we leave our own shores.

Propane or Butane? Nowadays most cookers are able to run with either gas as long as it is delivered to the cooker at the correct pressure, and by an amazing stroke of luck its the same pressure as delivered by the regulators available in the chandlers.  Butane is 28 mB and Propane 37 mB but strangely we found that in the Baltic Propane was delivered at a slightly lower pressure but it was not noticeable when cooking. So what's the difference?  Well, its all down to the pressure/temperature at which the liquid vaporizes i.e. turns from liquid in the bottles into gas.  Bottled Propane, at summer temperatures, is at about 100 psi i.e. about 5 times the pressure of Butane but both liquids happily vaporize hence the regulator can deliver gas to the appliances. However, as the ambient temperature falls there first comes a temperature at which the Butane ceases to form a gas, and this is at about zero degrees C; Propane continues to, I think, about 20 degrees C below zero. But in practice it is even worse because as the liquid vaporizes it takes heat from the liquid still in the bottle causing it to cool below ambient, thus at ambients below about 5 degrees butane is just about useless. Hence the almost total use of Propane in the cold of the Baltic and the very common use of Butane in the rest of N Europe.

Bottles? Most countries seem to have an own solution and they almost all differ from one another but some suppliers are good enough to recognize bottles from an immediately adjacent country. Finland and Sweden have limited supplies of each other bottles so will exchange them; similarly Germany and Denmark. But it surely goes without saying that, as the UK has no neighbors then supplies of bottles to suit our regulators are virtually impossible to find, when beyond our shores.  Except . .

Camping Gaz. I dont know where the home of this type of bottled Butane is, but its widely available in UK, France Spain and Portugal. And I discover that the question "Where can I get bottles of Camping Gaz?" in Greek is POU MPORW NA BRW FIALES GKAZIOU; so I suspect its available in Greece as well; certainly hope so. Other wise . . .

BBQ Gas (for want of a better name) I first saw this gas in France underneath a garden BBQ on a trolley. The connector is a press-fit on to the bottle, so really neat. Since then I've seen similar (note careful choice of word) in all of the Northern European countries, Finland to Portugal. My thoughts are that this could be a good one to standardise on. As a check, take your gas fitting with you and try it on another empty bottles at the store. A further alternative is . . . . .

Transferring gas between bottles. Corgi types read no further as the following is both dangerous and impossible. Phew, that's got rid of them. My credentials are simple; I've done it half a dozen times with Propane and it was easy. If you are interested in doing this then presumably you are low on gas and have at least one empty bottle and so you are risking everything and disregarding the opening warning.

What you need then is a "straight through" connector complete with tap for each bottle i.e. one which allows the transfer of either liquid or gas at an unrestricted pressure. The bottles can be of different manufacture as long as the receiving bottle is able to take the contents of the full one.  I'm thinking volumes and pressures here. Don't try put 5kg into a 4kg bottle nor Propane into a Butane bottle.  Next fasten the 2 connectors together with gas pipe rated at least 10 Bars (I used high pressure air line). That's the hard part done so a couple of simple checks. See if you can blow thro the assembly as you open both taps; close the taps and connect the assembly to the full bottle, then open the tap nearest the bottle and if all seems quiet wait one minute.  This latter check places the assembly under full bottle pressure but using gas as the pressure medium such that if a leak does occur only gas will hiss forth.

(NOTE: If a weakness had not been tested for and discovered here then a failure with the bottle inverted would have caused liquid to spurt forth resulting in an all together different and most hazardous situation) 

If all still seems well close the tap and suspend the bottle upside down from something; I used the bow anchor. Place the empty bottle on the pontoon and connect the tap/pipe to it. Open the lower tap then ask the crowd of imbeciles standing behind you to extinguish all cigarettes. Next simply open the upper tap and listen to the satisfying noise as the liquid descends to the lower bottle taking about 10 seconds to shift 2kg. Close both taps and check the bottom bottle now has liquid in it.

The first time I did a transfer I fussed no end, I cooled the bottom/empty bottle and left the full one in the sun to warm it. The aim being to make some differential pressure but I'm not sure if it did anything to help.  On subsequent occasions I simply fastened them together without the heating and cooling and listened for the whoosh. Its yet to go other than perfectly well.

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Health and Fitness

Neither health nor fitness have absolute values so what is described below is what we have done to maintain the levels of health and fitness we had before we became live-aboards. And, as we are both of above average H&F for our ages, we do have advice for all but the serious health freaks and fitness fanatics.

Living healthily.

coming soon

Diet and locally available foods.

coming soon

Exercise, onboard and on land.

One comment that we often hear, and its one to which we completely fail to relate, is that sailing  keeps you active and therefore fit.

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Shade from Sun and Rain

Coming soon

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Related web sites

This section has been transferred to the new links page. click here for Links Page

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Toilets

If one was to list 10 items we cannot live without I'd guess a toilet would come on most peoples list, so lets look after our loo.

Almost blocked poop pipe.
Almost blocked poop pipe.

As you know toilet pipes progressively fur up and loose the peak flow capabilities until one day they block up by something like a partially digested carrot. But what's really happening, why is it happening and what should we do to lessen the problem? I asked this question on the YBW forum and learned from Roger that:

in general, sea water is saturated with calcium bicarbonate which is formed by carbon dioxide and insoluble calcium carbonate. This comes from carbon dioxide dissolving in water and forming a weak acid which dissolves the calcium carbonate.

Then turning to the crux of the matter, urine is only slightly alkaline when produced but is attacked by microorganisms to produce ammonia and this is much more strongly alkaline. The alkaline ammonia solution reacts with the calcium bicarbonate to produce calcium carbonate again which is insoluble and forms the scale.  So now you know, but so what, what can we do to lessen the chances of a blockage, .

First of all lots of flushing will get rid of the urine before it has much chance to decay to ammonia, this is the first and best line of defense. Eventually, however, the calcium will build up and, although Peggy the Headmistress from the US (YBW forum) recommends regular flushing with white vinegar or Ascetic acid to further slow down the build up, one day it will block.  But which pipe is blocked?

A loo has a fresh water input to flush the basin and this pipe is usually clear, no urine so no Calcium; it seems we are now experts eh.  Secondly is the loo pee & poo output pipe which really does block but only as far as the anti-siphon or siphon-break in the top of the U leading down to the skin fitting.  Reason here is that the air entering the siphon break allows the fall pipe to empty to water level so no Calcium laden liquid to calcify the pipe. (This latter paragraph assumes no holding tank)

Being live-aboards we almost block annually but, interestingly, the fast build up due to daily use gives rise to a soft Calcium which is easily removed.  Remove the pipe and whack it on the pontoon (Mon to Fri is preferable so as to have a minimum of onlookers) and then refit the as-new pipe, remembering to clean the U siphon break otherwise next year will mean cleaning two pipes. Do note that rinsing the loo pipe with the pontoon fresh water supply, particularly during Sat and Sun, is to be avoided.

Agua Fuerta. Here in Spain and now Portugal we have found both a 20% and a 30% solution of Hydrochloric acid (Acido Hydrochloro)in the supermarcado and we are trying that down the loo on a weekly basis.

I add a small cup full to about 3 litres of warm water and put this on one side for a few moments whilst I vigorously flush the loo to eject any air from the system, I then almost empty the loo bowl ensuring no air goes into the pipes. Into the bowl I then pour the weak Agua Fuerta. My estimate is that 3 litre easily fills the pipework so I pump most of the liquid down the loo so filling all of the pipe with the weak acid solution. Then at 20 min intervals (or 2 hours if we forget) I flush the loo by pumping once up and once down on the handle. In doing this I aim to keep the solution moving down the pipe so all parts of it get to feel the acid, particularly by the sea-cock, which remains open and so maybe the acid is weaker in this area.

When we were lifted out in Lagos (Mar 07) sighting up the P&P pipe showed it to be clean. Yes I could only see about 250mm but I believe at this stage it represents the whole of the pipe.

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Holding Tanks

April 06 - skin fitting installed and tank installed but no plumbing as yet. March 07 - finally plumbed in and workng.

The tank is 60 litres, some say its far too small but we will see. I've fitted a 2-way valve on the pee-poo pipe from the loo so that the P&P can either go out through a 38mm sea-cock or into the top of the holding tank 2m away in the aft locker. The tank is vented by 15mm pipe which exits the boat about 300mm above the waterline so should be reasonably pong free. The output from the tank travels down 50mm inside diameter pipe to a 50mm sea-cock. In tests a full 60l of fresh water empties in about 20 seconds. The real stuff being a bit more solid might be slower me thinks.

Pump out via deck fitting - the deck fitting has yet to be installed so we can at the moment only discharge at sea but its only a small step to complete this job. One important point when emptying via the deck pump-out is to ensure the tank does not implode and to this end installations must have a high capacity vent in the system. This can either be a second 50mm deck fitting or, as we have, a large removable inspection hatch on the tank top.

One observation you readers might have made is that many installations do not have a second sea-cock to empty the holding tank as they use the existing P&P sea-cock. This is acceptable as a solution but the tank will not usually empty by gravity and so a large hand bilge-pump is fitted (henderson type). I felt that our solution, whilst sadly having an extra hole in the hull, was simpler in use.


And if you have read this far please now click on one of the adverts below. In doing so you will cause the advertiser to add a few cents to our cruising fund.

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