Alan de Enfield

You appear to have posted this an hour ago and then reposted it a few minutes ago

My Mercedes had a 170 amp water cooled alternator (too much leccy stuff !) and when it expired it was almost £500 to replace PLUS almost £500 in labour as so much had to be removed and the engine completely drained down and refilled.

And I'm with you - the discussion was steel vs other materials & his comment actually suggested that pumping out a steel tank cost less than a stainles steel or Plastic tank. But he has now clarified it that a stainless steel or plastic tank will have a higher cost of installation. Alles klar !

How does the material of the tank affect the cost of a pump-out ?

Are you including jennifers as 'alternators' ? (I suppose they should be included) If so surely that makes 5 for you (plus another 2 for me !) Edit - Ah - tricked me - of course your Tesla doesn't have an alternator !

It soon adds up 2 + a spare on each boat, then count the Digger, Dumper, Mower, Kawasaki Mule, the campervan and 2 cars

I'm a big fan of alternators - I have two of them. Edit - when I think about it, I actually have thirteen.

Both my grey and black water tanks are built into the GRP keel on my cruiser - that should never rust thru' either.

You are correct in what you say - but it should also be remembered that outboards have 'big issues' in use as well ............. 1) Petrol use and storage regulations 2) Petrol availability (but in this case the OP could pick up a can on his way home from work) and the 'biggy' 3) The lack of charging capacity with a small 5-8 amp alternator. He would be having to "live off" his 'portable power station' for both his 12v and 240v appliances.

In which case I stand corrected. I have had a number of boats with Webasto or Eberspacher fitted and they have all had a thermostat. I had a Webasto retro fitted in one boat and it came 'as standard' with a thermostat, so I was not aware that it was an optional extra.

Really - had you considered using that little dial called a thermostat ?

I think the point was that 50.05cm leaves only 0.25mm (1/4 mm) each side, but you are saying you have 1mm each side so it should read 50.2cm.

So, you are saying "save your energy for pulling the lever".

It tends not to be a huge problem on GRP yachts, but the process is well known in the sailing world, and, even affects wooden boats. From practical sailor magazine .................. The effects of overprotection on a fiberglass boat are usually not nearly as harmful as underprotection, but it is important to recognize the signs. On steel or wood hulls, over-protection can cause expensive damage if not caught in time. In any case, it is important to recognize the signs. Burnback. It is a common sight to see a discolored ring 8-12 inches in diameter around a bronze seacock. Typically there will be increased growth, the result of paint that is no longer functioning. In every case we found, there were several things in common: the fittings were bonded, the paint was high-copper, and there were additional zincs, beyond the single shaft collar. Based on a little testing, conversations with paint companies, and a little knowledge of chemistry, the cause is obvious; the same electron flow that is preventing copper and tin from leaving your bronze impellor has prevented copper ions from leaving the paint and repelling marine growth. There are various solutions that can be used alone or in combination with eachother: prime (several coats) all underwater metals before painting; reduce the number of anodes to achieve the desired voltage potential; switch to a less reactive anode material; switch to a copper-free paint; or switch to Marelon through hulls (reducing the amount of anodes required). Paint delamination. This is most often seen on aluminum boats fitted with magnesium anodes, but it is sometimes seen on steel hulls with zinc anodes. If the driving potential is too great, gas is generated under the paint, and the paint is lifted off. For an aluminum boat, the answer is aluminum anodes alloyed for seawater plus proper painting procedures. For steel hulls it comes down to good hull preparation and priming, and careful regulation of the potential. We have seen recommendations between 0.75 and 0.9 volts (relative to a silver chloride reference electrode), and the U.S. Navy uses 0.85 volts as their design requirement for cathodic protection systems. Regular monitoring is advisable. Caustic Wood Rot. If the driving potential is too great, bleach and caustic soda are produced around protected fittings. Since some of this reaction takes place inside the wood without seawater flush, the concentration of caustic will continue to rise and the caustic will begin to destroy the wood near the reaction site. Diagnosis is a simple matter of testing the pH of seepage or any powder near bonded fittings; if pH is greater than about 9.5, there is a problem. The solution is to limit bonding and zincs to the shaft/prop area. Less is more. A lower potential is typically recommended for wooden boats, about 0.5-0.6 volts.

I believe the problem is that todays 'youth' raised on a diet of social media and never being told they are wrong, & its alright to come last, you are just not yet ready for the challenge, etc etc etc does them no favours. When they get into the realworld ( of CWDF) and get told their idea is not practical and list the reasons why, they take the hump and never return.