Princess 33 re -engine?

[pappaecho]

My P33 has twin Ford Mermaids with 3800 hrs on each. Both start and run well, but I am starting to wonder if a 4 litre engine producing only 80 SHP is a bit out of date and can be replaced by something smaller and lighter with better fuel consumption.

The boat was originally supplied with Volvo petrol engines, 'cos there is still an ignition coil nailed to the engine bulkhead. No idea of what they were, but presume they were above 100 SHP so the boat could plane.

Wondering therefore about say twin 120 shp diesels. Any ideas?

 

[volvopaul]

My P33 has twin Ford Mermaids with 3800 hrs on each. Both start and run well, but I am starting to wonder if a 4 litre engine producing only 80 SHP is a bit out of date and can be replaced by something smaller and lighter with better fuel consumption.

The boat was originally supplied with Volvo petrol engines, 'cos there is still an ignition coil nailed to the engine bulkhead. No idea of what they were, but presume they were above 100 SHP so the boat could plane.

Wondering therefore about say twin 120 shp diesels. Any ideas?

Nice subject from my past, my dad had one in 1992 with the y hull so not a speed boat but would plane flat out at 14 knots, I often thought about at the time fitting a pair of bigger engines.

If yours is the planing hull version then maybe do it to gain speed, but if it's the y hull version I'd say don't bother as the fuel burn will be high for the size of boat.

If your thinking about fords sabre 120 Dover style engine you have to bear in mind the power to weight ratio.

I'd be looking at either, yanmars, 230 hp or a nanni from the same engine family.

Your a bit short on length as the mermaids right up against the forward bulkhead, although the Borg warner gearbox is very long, I'd ditch that to get in a different engine and gearbox.

If you stay with an inline box there will be less engine bed re design to carry out, most modern gearboxes are down angle, between 8 and 15 degrees, so the front of the engine is dropped down, which again if the sump is low some g r p work may be required to get the engine to sit right, it all sounds a bit of a minefield, the first way to attack is with the calculator! And ask yourself do you really want to spend that kind of money on an old boat, or put the cost towards another boat. I recently spotted a Mark 2 fly 33 with petrols in for 16k, which would take a nice pair of kad 32s and drives nicely with a bit of change for the old motors and drives.

Pm me if your interested in me taking a look, I've done many engine swaps over the years.

 

[oldgit]

"Wondering therefore about say twin 120 shp diesels. Any ideas? "

Lets ignore the costs of re engine and poss new shafts/props and poss gearboxes (20 -30K ?) and the fact that any "classic" boat with new engines is only going to command smallish premium over one with old ones.

My old P33 had 2 x AQD40A on nastydrives, engines allegedly developed 135 hp and best we could ever muster was 15-16 knots.
The later MKII with 158 hp engines was supposed to get over 20 knots,but I doubt that ?

 

[Pete7]

If they are Ford Dovers, Mermaid managed to get 198 hp out of this one on the dyno for me. Might be worth having a chat with them. Even in RN spec they gave 140 - 160hp. Be a lot simpler than changing to a different engine.

Pete

 

[Latestarter1]

If they are Ford Dovers, Mermaid managed to get 198 hp out of this one on the dyno for me. Might be worth having a chat with them. Even in RN spec they gave 140 - 160hp. Be a lot simpler than changing to a different engine.

Pete

Cyril Snare is long retired and Mermaid is sadly no longer Mermaid. Ford Dovers are history, replacement pistons are £200 a pop if you can still get them. Mermaid were re-ringing pistons on rebuilds 15 years ago.

Little Yanmar 4HLA would be nice with Kanzaki box but the cost..................

 

[pappaecho]

OLdgit, on a slightly different topic you have just posted the working diagram on the BW 72 gearbox. Was this fitted to your old Princess?

You are right of course filling new egines is a no no. But what about slightly used engines, and admittedly need marinising with Bowman kit?

VolvoPaul has kindly confirmed that the Y shaped hull is a very good way of burning £50 notes with no real effect.

At the moment the Mermaids are fine if little smoky, but at near 4000 hours they are going to need serious attention fairly soon

 

[volvopaul]

Pappa, re the ignition coil, I've never heard or seen a shaft drive petrol 33, I'd say the coil looking item is a diode blocker for the charging system.

If our serious about engine swap I do know of various yanmars and volvos that can be resurected back to life for such an older style of project.

 

[oldgit]

Smoke...Ha ...you need to speak to Divemaster or HLB.

" on a slightly different topic you have just posted the working diagram on the BW 72 gearbox. Was this fitted to your old Princess?"

Nope.the old girl had 280 crapdrives so no gearbox as such.

Latest boat has got the 72C gearbox with 2 x Perkins M135 engines.
No Turbo
No Electronics
No over-priced spares
No Trouble and cheap to run.
Will push my present boat around 36ft and 8 tonnes to 16 knots on good day.



"At the moment the Mermaids are fine if little smoky, but at near 4000 hours they are going to need serious attention fairly soon"


If they merely smoke until warmed up with the odd puff after that would use them until something breaks which could be years and years away.

 

[pappaecho]

VolvoPaul be amazed. The boat is fitted with Volvo controls, and has two petrol filler points on the stern - port and starboard but the tankage has been removed.The diesel tank has a single filler at the front of the cockpit, with the tank midships under the cockpit.
The original sale documents indicate "twin petrol" but not what!
the boat is 1978: the Mermaids were fitted in 1982