Best 3 cabin boat/engine combination

[David435]

Hi All
I'm hoping to pick the brains of the forum in guiding me to the best boat /engine combination.
We are currently selling a 1990 Princess 435 with TAMD61A (306hp) engines, both engines were removed in 2015 by a main agent, inspected and overhauled where necessary. The only disappointment we have found with this boat is the engines appear to be slightly under powered for the size/weight as the engines produce a max. 2800 rpm and cruise at 2500 rpm between 15/17 knots. The boat itself has been marvelous and very seaworthy with the 3 double cabin layout which we find most suitable for our needs but would now prefer the sedan style with rear door access to the bathing platform. We currently cruise the south coast from the Solent to Cornwall and make regular trips to the Channel Islands. Our budget would be approx. £90,000 and accept we will have to purchase a 1990 - 1995 model in excess of 46ft. We have come across Fairline 50 with Cat 3208, Princess 470 with TAMD72 (430hp) and Princess 55 with Volvo 480hp but have no idea if the engines have adequate power or are considered reliable. We would appreciate help from the forum in confirming if any of the above combinations are good or should have a different power units or suggesting alternative 3 cabin boats in our price range together with the most suitable engine configuration that should provide enough power for the size of boat and offer reliability
Thanks a lot for your advice.

 

[kashurst]

tricky one, the 3208 has a very good reputation, the TAMD 72 - maybe not, the princess 55 which engine is that?
re boats have a look at Astondoa 45 and the 46 - quite a few for sale in Spain, much newer, three good cabins, you may get one within your budget. Not well known in the UK so may be harder to sell on later but probably easier to sell than a 1990s 50 footer. Build quality arguably not as good as a Fairline etc but strong where it counts. All the ones around me seem to float OK and they will do @ 28 knots in the med. Heavily built hulls. Buying in Spain not difficult - stick it on a lorry to a French port and sail to the channel islands. Have a loog at the Top Barcos website - some bargains in there. Contrary to popular opinion on here there are other manufacturers than Fairline/Princess/Sealine - some of which are very good.

 

[David435]

Thanks for your reply.
As far as I know the Princess 55 engine is a Volvo 75P

 

[kashurst]

the 75P is a quality motor, not sure how much performance it will give with a 55 footer , whats the displacement of the 55??

 

[David435]

I've just looked up on the Princess heritage site and the displacement is approx. 15,500 kgs. It also stated that engine option 1 at 480hp was a TAMD 122 @ 480hp and not the 75P, option 2 was a Caterpillar 3208TA @ 425hp and option 3 was a TAMD 71A @ 358hp. The 75P is not mentioned so probably irrelevent. I would have thought the TAMD 71A would have been better suited for my Princess 435 and would really struggle to push along a Princess 55.

 

[Whitelighter]

Wow, my 50ft boat of similar vintage has twin 550hp motors and is far from a speed machine

 

[David435]

Hi Whitelighter
I've just looked up a Princess 55 for sale and the broker is advertising 20 knots cruising and 27 knots max speed using the Volvo 480hp engines. As your Ferretti is 10% shorter and presumably a lighter displacement weight, then in theory your twin 550hp motors should achieve the above speeds at least. These speeds would be more than adequate to me as to be able to operate on days at cruising speed and remain comfortable can be few and far between especially in UK waters. This is why I started this thread as I don't want to waste time with brokers looking at boats with engines that are simply underpowered for the size/weight of boat in question. I am leaning towards the Caterpillar option but at 425hp will the engine produce enough power to achieve the advertised speeds above. I have no experience whatsoever with any of these engines but reading other threads the consensus appears to support the V8 low revving Cat over the higher revving 6 cylinder Volvo.

 

[Hardmy]

I'll resume what I've been told in this parish, when I bought my boat with 3208 CATs. While the 3208 in its natural version has a very good reputation, the 3208TA (425hp) extracts quite a lot of ponies out of this block, hence is more prone to overheating. If maintenance is not neglected, there is no reason to worry though. I have done 400-500 hours with them without any problem. For peace of mind, I fitted a temp exhaust alarm which would go off before the engine overheat alarm, for example should a for example a raw water flow disruption occur. I'll achieve only 18-19 kts WOT with them, but the boat is heavy (around 22 tons / 48').

I don't want to tell you the obvious, but in a 1990 boat (like mine) the shaft seals might need a close check. I decided to swap them with Tides Sure Seals...

 

[Portofino]

I would say v8 cat of similiar displacement less than 10% difference going fwds will be better than a 6 Volvo .
The point you make about revs in old engines IMHO is important , lower the better .
@ cruising speeds ( not max wot power ) a lazy cat burbling away low down will produce more torque -turning power than a higher reving striaght 6 .

You could google the torque curves for both .
That said one assumes after 20-30 y both boats have been correctly propped ,which I,am sure is the case .

Low down torque from a v8 depends on the stroke .
A long stroker has a bigger block less compact ,wider = install issues .
Think byclcle crank -longer more turning force .
A short stroke crank ,d V8 can be cast in a more compact block easier to install wider market .It will rev more cos less distance the piston moves ,have less turning force torque, but arguable on paper at least @ the higher rpm more Hp .
But is that useable ? Rpm high up ? In a boat .Racing car yes !

Higher reving anything has grater piston acceration and velocity .
Less distance to speed up and then slow down .More times /minute .
All this puts more lifetime stress on all the internals .
Increases wear

New F1 engines last about 500 miles .@ 18,000 rpm

So old diesel engines go lower rpm wise .
Another killer is exhaust gas temp .
Because diesels are effectively air pumps with a touch of oil carefully squirted in at the right moment ,they are hot to start with before the oil bit .
The way the pumps work ,throttles and the prop demand -it's possible to end up in a situation of overloading them -for too long
You can,t do this to a car. It has gears and you can tell if it's labouring -petrol or diesel .
In a boat Kg -weight and In correct propping --the "one gear "
All play a part .Drag in terms of fouling -you can adjust -clean it ,scrub it etc .
The rest you are stuck with .
So if I read your post correctly you are one of the very few on here that is actually looking @ weight and power /weight ratios .-V important in old boats .
Hats off to you .

I think it fair to say as old engines age they loose a % of power as the years /decades pass .
So if it's on the edge in a new mag report and stuffed with Kg as the years pass
Then planning will get harder and harder ,or the engine has a tendency to nudge towards overloading and raised EGT,s ---- short life

This is why "Marine "diesels pack up after seemingly low hrs /sea miles compared to automotive trucks 100 000 Kms +

My boats done 24000 miles according to the plotter .

 

[Portofino]

I'll resume what I've been told in this parish, when I bought my boat with 3208 CATs. While the 3208 in its natural version has a very good reputation, the 3208TA (425hp) extracts quite a lot of ponies out of this block, hence is more prone to overheating. If maintenance is not neglected, there is no reason to worry though. I have done 400-500 hours with them without any problem. For peace of mind, I fitted a temp exhaust alarm which would go off before the engine overheat alarm, for example should a for example a raw water flow disruption occur. I'll achieve only 18-19 kts WOT with them, but the boat is heavy (around 22 tons / 48').

I don't want to tell you the obvious, but in a 1990 boat (like mine) the shaft seals might need a close check. I decided to swap them with Tides Sure Seals...

Posts x

 

[volvopaul]

I've just looked up on the Princess heritage site and the displacement is approx. 15,500 kgs. It also stated that engine option 1 at 480hp was a TAMD 122 @ 480hp and not the 75P, option 2 was a Caterpillar 3208TA @ 425hp and option 3 was a TAMD 71A @ 358hp. The 75P is not mentioned so probably irrelevent. I would have thought the TAMD 71A would have been better suited for my Princess 435 and would really struggle to push along a Princess 55.

The 75p 480 wasn't around when the P55 was created , the 71A was its predecessor at 6.7 litres .

My view would be the Princess 55 with the 122D engines in is bulletproof as it's a 12 litre block.

The Cat 3208 is also a good unit but dates back to the 1950s as an industrial engine which lacked serious development, there was also no piston cooling capability which limited its hp output before things got serious. It bowed out with a sliver anniversary edition at 442 hp, some were installed in the Princess 440 before the TAMD 74 was introduced which gave a far better hp to weigh ratio.

 

[David435]

Hi Volvopaul
Thanks for your input, it is greatly appreciated. After your suggestion the TAMD 122D engine in your opinion would be the preferred option, I have trawled through google to try and find the the power output details without success. Do you know the the max. revs WOT for the 122D and whether the economical cruising revs are 300 less than WOT as is the case with our TAMD 61A in our Princess 435.

 

[volvopaul]

Hi Volvopaul
Thanks for your input, it is greatly appreciated. After your suggestion the TAMD 122D engine in your opinion would be the preferred option, I have trawled through google to try and find the the power output details without success. Do you know the the max. revs WOT for the 122D and whether the economical cruising revs are 300 less than WOT as is the case with our TAMD 61A in our Princess 435.

A 122D in the right boat will be a fairly flat curve once on the plane , from memory there flat out at 2300 rpm so 2100 is quite doable , it's the last 200 rpm on most engines where the fuel burn gets scary .
122D if looked after will give thousands of hours service as it's 12 litre capacity hardly needs the turbo to produce its horses .