re-engine. Does it (ever) make sense ?

[aquapower]

Btw, did you scrap them? Since they were also the original Acquarama engines, sometimes you can find people willing to pay decent money for them....

Its says in #17 above where old engines went, it sounds like a good investment to me

 

[MapisM]

Said it before..........Gasoline is for girls!

LOL, yeah, yeah....
...Shame that a 1:1 power to weight ratio is a dream for most diesel engines, while some girls can achieve more than DOUBLE of that!

 

[MapisM]

Its says in #17 above where old engines went, it sounds like a good investment to me

Ops, I completely missed that.
Good investment? Investment alone is a word that has no place in a boating forums, but coupled with "good" it becomes even laughable...!

 

[Jegs]

Ops, I completely missed that.
Good investment? Investment alone is a word that has no place in a boating forums, but coupled with "good" it becomes even laughable...!

Correctly called "upgrading the boat."

John G

 

[dustywings]

Said it before..........Gasoline is for girls!

Question for Dustywings. Riva did a decent job getting some height into the exhaust system can we see how you configured the risers to achieve the same end, on the face of it fast running out of under deck space.

I had custom risers made that went as high as the engine room would allow, this gave me height/down angle well above the Sabre recommended minimum, I am afraid I cant find a photograph to show.

 

[dustywings]

Whoa, I almost can hear the sound of those lovely 454 big blocks just by looking at your pic!
Were you planning to build up a LOT of cruising hours, and/or were those engines completely knackered?
For the typical yearly usage of a boat like the Bravo, I for one would have considered saving whatever you spent in repowering and keep burning petrol!
Btw, did you scrap them? Since they were also the original Acquarama engines, sometimes you can find people willing to pay decent money for them....

As highlighted, yes I sold them to a chap who had two classic Rivas, as for their condition they had supposedly been overhauled a year before I purchased the boat but they would not get the boat above 25 knots even with a clean bottom and half fuel and water.

 

[MapisM]

LOL, why am I not surprised? Two perfectly running Riva Crusader 350hp are a rare find for someone involved in restoration of classic Rivas.
Though it's pretty obvious that the overhauling was not properly made, because if you are now making 34 knots with 600hp, it doesn't make any sense that 700hp could only give you 25 knots.
Better holeshot with the diesels (even with less hp), that might be possible. But higher top speed with less power, no way.
There was obviously something very wrong with those blue girls. Though not necessarily something too expensive to fix....

 

[Don Pedro]

J'ai un vieux (1987) Riva Bravo que je garde et que j'utilise dans le sud de la France. C'est un bateau parfait pour ce pour quoi nous l'utilisons et il y a peu de choses que je changerais dans sa conception générale et certainement la qualité de la construction est extraordinairement élevée. Il y a un hic... elle a des moteurs Cummins VT 555, qui ont été reconstruits par un propriétaire précédent (à grands frais ! - je veux dire vraiment énormes !)..... mais ils sont malodorants et enfumés et très bruyants. C'était le moteur que Cummins n'aurait jamais dû fabriquer et ils pèsent plus de 1000 kg chacun tout en produisant (au mieux) 320 ch. Dans un bon jour, ils lui donneront 32 nœuds à fond, et il navigue assez bien à environ 26 nœuds quand il n'y a pas trop de monde à bord, mais dès qu'elle est chargée, les performances commencent à chuter et j'ai même été renversé de l'avion par un gros sillage ....... Alors que faire ? Ma première pensée est que c'est un bon bateau qui me va bien, mais que je veux aller plus vite. Nous faisons principalement de courts trajets (7 à 10 miles) dans des eaux principalement plates et ce serait formidable de pouvoir naviguer à 30 nœuds ou même un peu plus. Donc la chose logique est de la vendre et d'obtenir autre chose. Je pense que j'obtiendrais environ 50 000 £ pour elle, donc j'aurais besoin de mettre disons 100 000 £ en plus si je voulais obtenir quelque chose comme un Windy Grand Bora qui me donnerait cette performance tout en offrant le genre de cockpit massif et d'espace de bronzage qui J'ai besoin.
Je n'ai pas encore impliqué d'ingénieur ou d'architecte naval, mais le six cylindres Yanmar de 480 ch est plus petit que mes monstres existants et pèse 640 kg chacun contre 1023 kg chacun des anciens. Cela signifie que j'aurais probablement besoin d'ajouter du poids au milieu du navire, mais je pourrais le faire avec du ballast ou peut-être un réservoir de carburant supplémentaire. Le HP supplémentaire devrait me donner une vitesse de pointe de près de 40 nœuds afin que je puisse naviguer confortablement dans les 30 bas où le bateau se comporte avec brio ...... Les boîtes de vitesses devraient changer mais il y a de fortes chances que les arbres et l'arrière puissent rester (ils sont massivement construits) ...... pas sûr.
Je sais que je suis fou (nous le sommes tous sinon nous n'aurions pas de bateau du tout) mais suis-je complètement fou... ou juste un peu fou ? Toutes les pensées, opinions et expériences sont les bienvenues.

BB
[/DEVIS]

I have a an old (1987) Riva Bravo which I keep and use in the South of France. She is a perfect boat for what we use her for and there is little that I would change about her general design and certainly the quality of the build is extraordinarily high. There is one catch....she has Cummins VT 555 engines, that were rebuilt by a previous owner (at vast expense ! - I mean really vast !)..... but they are smelly and smoky and very noisy. This was the engine that Cummins should never have made and they weigh over 1000kg each whilst producing (at very best) 320 hp. On a good day they will give her 32 knots abosulutely flat out, and she cruises at about 26 knots quite well when there are not too many people on board, but as soon as she is loaded up performance starts to drop off and i have even been knocked off the plane by a big wake....... So what to do ? My initial thought is that she is a good boat that suits me well, but that I want to go faster. We mostly do short trips (7 to 10 miles) in mostly flattish water and it would be great to be able to cruise at 30 kn or even a smidge over. So the logical thing is to sell her and get something else. I think I would get about £50,000 for her so would need to put say £100,000 on top if I was going to get something like a Windy Grand Bora which would give me that perfromance whilst still offerring the sort of massive cockpit and sunbathing space that I need. I would consdier other models but they need to be around the 40 ft mark (42 or 43 max) and they need to be quick whilst still being able to sit 8 people round a table for lunch (which rulesout all the "fast" boats like Huntons etc)...... But it did cross my mind that if I spend £100,000 on a massive engine upgrade and general refit I could make my existing boat perfect whilst still keeping my running costs low (The Riva is shaft driven and a joy to drive and to handle, plus she is cheap to maintain)...... of course the finished product would not be worth much more than £100,000 at best so it would be capital destructive but so would owing a £150,000 windy whereas the Riva doesnt or shouldnt depreciate much.
I havent got an engineer or a naval architect involved yet, but the Yanmar 480 hp six cylinder is smaller than my existing monsters, and weighs 640 kg each vs the 1023 kg each of the old ones. This means I would probably need to add some weight amidships but I could do that with ballast or perhaps an extra fuel tank. The extra HP should give me a top speed of nearly 40kn so I could cruise comfortably int he low 30's where the boat handles brilliantly...... Gearboxes would have to change but there is a good chance that the shafts and sterngear could stay (they are massively built)......not sure.
I know that I am mad (we all are otherwise we wouldnt own a boat at all) but am i completely mad....or just a little bit mad ? All thoughts, views and experiences welcome.

BB

Hello, I am new to this forum and I discovered your conversation from 2014 about your wish to re-engine your RIVA Bravo.
I would be interested to know what was your choice.
At the end, have you changed your old Cummins?

 

[harvey38]

I also have a Riva Bravo and have done what you are considering! I decided on a Bravo and looked at several all with the 555's then ended up buying one in Ibiza that had the Riva Crusader petrol engines as the price meant that I could repower it. I agree that if you are going for new engines then it simply doesn't stack up however I do my boating on a budget and bought a second hand pair of engines that had done 600 hours and been very well looked after. I did the majority of work myself but the finished result has been superb. The saving in weight over your engines was around 750kgs in total so I have a pair of 300hp engines which mean I cruise at 2000 rpm giving 23 knots and use 66 lph, top speed is 34 knots.

I went from this:

To this:

To this:

Very happy to discuss in any detail about my work and good to hear there is another Bravo owner on the forum!

I love our 6cyl 250hp SABRE lumps but could do with some 'Smoke management' on start up, have you found anything to minimise it or are you like me, start up and dash?

 

[BB1]

I have a an old (1987) Riva Bravo which I keep and use in the South of France. She is a perfect boat for what we use her for and there is little that I would change about her general design and certainly the quality of the build is extraordinarily high. There is one catch....she has Cummins VT 555 engines, that were rebuilt by a previous owner (at vast expense ! - I mean really vast !)..... but they are smelly and smoky and very noisy. This was the engine that Cummins should never have made and they weigh over 1000kg each whilst producing (at very best) 320 hp. On a good day they will give her 32 knots abosulutely flat out, and she cruises at about 26 knots quite well when there are not too many people on board, but as soon as she is loaded up performance starts to drop off and i have even been knocked off the plane by a big wake....... So what to do ? My initial thought is that she is a good boat that suits me well, but that I want to go faster. We mostly do short trips (7 to 10 miles) in mostly flattish water and it would be great to be able to cruise at 30 kn or even a smidge over. So the logical thing is to sell her and get something else. I think I would get about £50,000 for her so would need to put say £100,000 on top if I was going to get something like a Windy Grand Bora which would give me that perfromance whilst still offerring the sort of massive cockpit and sunbathing space that I need. I would consdier other models but they need to be around the 40 ft mark (42 or 43 max) and they need to be quick whilst still being able to sit 8 people round a table for lunch (which rulesout all the "fast" boats like Huntons etc)...... But it did cross my mind that if I spend £100,000 on a massive engine upgrade and general refit I could make my existing boat perfect whilst still keeping my running costs low (The Riva is shaft driven and a joy to drive and to handle, plus she is cheap to maintain)...... of course the finished product would not be worth much more than £100,000 at best so it would be capital destructive but so would owing a £150,000 windy whereas the Riva doesnt or shouldnt depreciate much.
I havent got an engineer or a naval architect involved yet, but the Yanmar 480 hp six cylinder is smaller than my existing monsters, and weighs 640 kg each vs the 1023 kg each of the old ones. This means I would probably need to add some weight amidships but I could do that with ballast or perhaps an extra fuel tank. The extra HP should give me a top speed of nearly 40kn so I could cruise comfortably int he low 30's where the boat handles brilliantly...... Gearboxes would have to change but there is a good chance that the shafts and sterngear could stay (they are massively built)......not sure.
I know that I am mad (we all are otherwise we wouldnt own a boat at all) but am i completely mad....or just a little bit mad ? All thoughts, views and experiences welcome.

BB

I've re engined a few boats that never made financial sense and when I've bumped into the customer a few years later they have all said it was the best thing they have ever done.
Do it properly...check shafts and inboard bearings, replace battery cables and water inlet hoses etc, etc, etc. You will lose money if you sell the boat straight on but as the years go by the cost pays off, if you love the boat don't rule it out.

 

[dustywings]

I love our 6cyl 250hp SABRE lumps but could do with some 'Smoke management' on start up, have you found anything to minimise it or are you like me, start up and dash?

Yes mine were smokey on start up too but better than the previous generation (Dorset vs Dover) and not that bad. If I remember coccectly there was a device you could fit that would allow them to start up on fewer cylinders which would reduce the smoke until they warmed up.

 

[dustywings]

I love our 6cyl 250hp SABRE lumps but could do with some 'Smoke management' on start up, have you found anything to minimise it or are you like me, start up and dash?

Yes mine were smokey on start up too but better than the previous generation (Dorset vs Dover) and not that bad. If I remember coccectly there was a device you could fit that would allow them to start up on fewer cylinders which would reduce the smoke until they warmed up.

 

[Gushter]

I have an old Riva Superamerica 48 that was re-engined by the previous owner. I think it makes a lot of sense if you love the layout and condition of the old boat. Riva's age gracefully, so it could make a lot of sense. It is best to stay close to the original design in terms of HP (in my case it was 420 hp to 450 hp) and the same make (Cummins in my case). Otherwise, you need to change the gearboxes, the electronic throttles, the shafts and the propellers and this becomes a major expense. Given the fuel prices today (assuming they do not go down), the capex will be a small cost. I made the following calculation. Current engines have 1,000 hours on them. Say I put another 1,500 hours before I need major work on them. That is 1000 hours x 120 litres/hour average x Eur 2.20 = Eur 400k in fuel costs. Clearly, fuel will dominate the total expense of running the boat for the next 5 years. You could probably justify the cost just by improved efficiency and greater satisfaction.

The reverse of this is that power boating may get banned or restricted soon with all this green economy stuff. Then it is not the smartest to upgrade the engines.