Well, I've finally done it - couple of weeks ago, I made the decision to buy new engines for my rib, rather than a hard boat...
My main concern about getting the hardboard, was the engine - it was an older engine, with no warranty... a big diesel, which I have been told aren't incredibly reliable.
I had a look around, and it was a close decision between twin optimax or twin hpdi, but for me the hpdi added a couple more benefits - they could use the existing dials/control cables etc I already have fitted - saving me making a possible mess of my console, and also I knew and trusted the guys who were putting them.
The fitting of the engines was carried out by Warsash Marine, and they've done a VERY good job of fitting them, very quick - and they put up with my constant nagging "are they nearly done yet..."
I took the boat out last wednesday night for the first time, and had been told to keep the revs below 2000rpm, so I was trundling over to cowes at 1800-1900rpm, all of about 13 knots, took a while, I think its the slowest i've ever done it
Got to cowes, and planned to go up to the folly for dinner, but stopped at cowes rib park to get a coffee... I took the owners manual with me so I had something to read .... I started reading the section in the manual about breaking in the engines, and found that I could run the engines a bit harder.. in fact...
First 10 mins, high idle...
Next 50 mins, no more than 3000rpm
Hours 2 and 3, no more than 4000rpm, but can burst to full throttle for 1 min, and then let cool for 10 mins at 4000rpm.
Then for the last seven hours you can run "as normal" but dont do WOT for more than 5 mins at a time.
So I did as it said, and scrapped the folly idea, left cowes, and ran it at 3000 rpm for a bit, got about 27-29 knots, then up to 4000rpm... abot 40 knots, and then full throttle, and was thrown back in my seat - I hit 51.6 knots!
Since then, i've had her up to about 53 - all still within the recommended RPM allowance in the manual.
The engines have 23" s/s props at the moment, and i'm getting about 5100 rpm.
At 4000rpm, 40 knots - I get about 60litres an hour, which is a very nice cruising speed, and not a bad consumption for twins. - Teh same speed in my old boat was costing me about 80/litres/hour.
The boat rides a lot nicer too now, much comfier at 40 knots than before, the engines bring another 20kg each so that helps, but also - theres still a lot of power left at that speed.
I am definately sure i've made the right choice between new boat or new engines, and am very pleased with the results!
Hope to see some more boats out soon, doesnt seem to be anyone "cruising" at the moment - I guess its the weather/time of year.
