Ex-Lifeboat engines

[bedouin]

FWIW the guy in Poole who sells these by the pallet load gets them as Freshwater cooled and converts them back to direct raw water cooling before selling them on, so when you get it it will not have actually been used with direct raw water cooling

 

[vyv_cox]

I am hesitant to question a statement from someone as knowledgeable as Vyv, but my understanding (perhaps mistaken) is that the keel cooled ones are not raw (i.e. sea or river water) cooled, but freshwater (with anti-freeze) cooled in a closed system. These have a 'circulation' pump, but no raw water pump. I believe such circulation pumps, by virtue of their design, materials and lack of a removable impellor, are unsuitable for use for raw water and the debris and salts that involves.

For subsequent indirect cooling use (i.e. without the keel cooler) these lifeboat engines would need the addition of a raw water pump and heat exchanger (as per my earlier post).

For subsequent direct seawater cooling (though I can't see the point if you already have the circulation pump) you would still need a raw water pump added, but no heat exchanger would be required and the circulation pump would be redundant.

Just for completeness, I'll add that the throughput volume required of the raw water pump and circulation pumps are very different, and that required of the raw water pump is somewhat higher for indirect cooling than direct cooling (same pump, different cam). E.g. for DV 36
COOLING WATER SYSTEM (Direct cooling)
COOLING WATER TEMPERATURE . ........................................ ......................................50 – 70oC
TYPE OF CIRCULATING PUMP / CAPACITY AT 3600 rpm...... ..............................CENTRIFUGAL / 24-30 Litres/min

COOLING WATER SYSTEM (Indirect cooling)
COOLING WATER TEMPERATURE . ........................................ ......................................70 – 95oC
TYPE OF SEAWATER PUMP / CAPACITY AT 3600 rpm .......... ...............................CENTRIFUGAL / 36-42 Litres/min
TYPE OF FRESHWATER PUMP / CAPACITY AT 3600 rpm ..... ..............................CENTRIFUGAL / 135 Litres/min
COOLING WATER CONTENT .......... ........................................ .........................................7.0 Litres

Yes, that is what I am saying. The keel cooled engines have antifreeze coolant in them. As sold for yacht use they will become seawater cooled for the first time. Keel cooling is used because the lifeboat may be required to motor through oil and debris (and fire, hence the closed lifeboats have water sprays over the decks.)

 

[Beneteau381]

Oh no! Now you tell me!

Seems strange that the triples would be that different to the singles and twins that preceded them in such a basic thing (though it is a different engine - the layout is different to that shared by the singles and twins), and that if it is a known weakness they haven't noticeably addressed it in the 40+ years they've been in production. (Not that the latter would help me: mine is one of the very earliest of the DV triples.)

Mate in Gib, had the issue of milky oil. Head gasket changed to no avail. He did some googling, liner O rings, he decided to fit a new Beta. He took the old one out and dropped the sump whilst it was suspended on a couple of blocjs of wood

 

[Beneteau381]

Head underneath and you could see the water dribbling from the liners.

 

[Refueler]

Earlier post illustrates different running temperatures and pump volumes between raw and indirect cooled.

Good reason for this. Raw water cooled is colder running to avoid depositing salts in waterways - you have no 'cleaner' in raw water.
Indirect cooling can run at higher more optimal temperature because of the fresh-water / anti-freeze mix without salts etc. You also have additives in the anti-freeze to clean / reduce corrosion.

As regards pump volumes - the figures are good enough on either to run raw water ... its not as critical as some may suggest. Think about it .... a boat running in North Sea temperatures - to a boat running in Caribbean .... same pump volume etc. but significant difference in seawater temp.

 

[TopBanana]

My current boat had one of these engines fitted a couple of seasons ago. Went down to start her this weekend for the first time in a few months. Forgot how sweet and smoothly it ran.