To planing flybridge owners: are you aware of how your boat performs...

[MapisM]

I don't think its a lack of interest, but most posters have something else to do between 2 and 9am on a Saturday morning, than lurking on the forum

LOL, touché...

All understood/agreed, anyway.
IIRC, the prop pitch is what we were most unsure of - also because for all other parameters it's easy to get accurate numbers (ratio is on the g/box plate, rpm can be slightly incorrect but not much, particularly when checking the consistency on both helms, and gps SOG is more than good enough - the difference with STW being irrelevant, in the Med).

Out of curiosity, which is the min/max speed achieved by BA at constant rpm (say 2000), depending on max/min load?

 

[BartW]

IIRC, the prop pitch is what we were most unsure of -

correct,
comparing prop slip between different boats would be interesting, (comparing hull shape, weight size ratio, prop diameter or number of blades, etc etc, etc...
but than again there are so many parameters that can variate that it would be difficult to make concusions ?

Out of curiosity, which is the min/max speed achieved by BA at constant rpm (say 2000), depending on max/min load?

somewhere between 17.5 and 21.5 knots,
but again, so many parameters that vary,

I remember just ones, many years back, first winter owning her, when sailing from france to Rome, fuel almost empty, without all the extra load from additions that came later: no platfrom, no stabs, no scuba gear, clean hull, that I acheeved approx 22 knots at 2000rpm,
Than again at that time I wasn't sure of the accuracy / adjustment of the analog rpm gauges.

lately somewhere between 18kn and 20kn, but we didn't sail much at 2000 rpm, and usually loaded with >50% fuel and water

the difference with a heavy loaded (fuel) boat is clearly noticeable,
but I avoid pushing her at 2000rpm fully loaded

 

[MapisM]

Interesting, thanks! :encouragement:

 

[Whitelighter]

Re: Slightly o/t, but somewhat related

I have a those numbers in the very comprehensive Ferretti leather book.
It's on the boat but I'm back out in April

 

[Portofino]

Will your prospect supply the info ,original prop slip data next week @ sea trail ?

Thing is if there's a discrepancy from your new calcs , to the oringinal - highly likely due to the many variables x years apart .
Is that a good enough reason to reject it ?

I had a good look around with the skipper , checked the history ,They were recommisioned 40 hrs and 4 months ago by a big Roma MAN agency after a 3/12 year lay up in a hanger .
There were some obvious new parts on them. Mostley Senders and one had a new turbo .

Ask if you can WOT it ,ck the guages are steady except the speed .
Check for abvious weeps n seeps before during and after .
Nice to see genuine filters used ( I know a lot on here us pattern parts ) but i like to see it .
I think I've put on 160 hrs uneventfully in the past two seasons with basic annual service ,oil n filters .
No error codes except low coolant pressure - once - leaky header tank cap gasket -- known MAN issue ---the rubber developes a "set " and eventually leaks -- the more you keep opening it up to look ,( when cold ) the faster it fails !-- supermarket bag as a temp gasket-- new cap € 70 for the large ,€50 for the small --- now carry spares .

I'll get agents in for the 1000 hr biggie .

Btw I sea trailed mine without a deposit ,just like buying a car really .Took a 2nd pair of eyes ,pair of us handy with spanners .


Hope it all goes well and you hit it off with the owner and broker leading to a sucessful new purchase .

Not quite sure what effect ( if any ?) sliding across the table your prop slip calcs ,will have on the realtionship ??

 

[MapisM]

I've already got the initial report in my hands, that's the 7 pages thing I mentioned earlier!
Rather impressive, btw. More about that in a few days, all going well - touch wood.

No need to "invent" reasons to reject the boat, anyway.
I asked to have the preliminary agreement modified in order to have incontestable discretion on the acceptance of the seatrial results, so I might reject the deal just because I feel like it.
Not that I want to, of course. And neither I'm going to be worried if the results will not be 100% aligned with the initial tests made 13 years ago: I'll be realistic in evaluating any deviations, and I'm far from expecting to find none.
But to make such evaluation, it's nice (no, wait, I'd say crucial, rather than just nice) to have firm numbers taken on the same boat when new, to start with.
Otherwise, on which basis can you judge the overall boat performance, not to mention all the specific parameters?
Using the builder specs, I suppose. Which is better than nothing, but typically you don't get much more than the max speed from those brochures, and sometimes even expressed as a range...
The initial seatrial with the engine manufacturer engineer is a MUCH more technical document, which has even legal implications.
That's in an entirely different league vs. any marketing BS (ops, I meant leaflet...)

Ref your last question, as just explained I don't need any excuse - let alone use prop slip as an argument, I wouldn't even dream to do that!
I just thought to ask here out of curiosity as I said in the OP, because it popped to my mind that it's one number for which I have no comparison with other similar boats. Nothing else! :encouragement:

 

[MapisM]

Re: Slightly o/t, but somewhat related

I have a those numbers in the very comprehensive Ferretti leather book.
It's on the boat but I'm back out in April

It's good to have them J, also because they might give a hint ref. the lower max rpm that you are getting.
I mean, as a general rule the initial tests should be done with the boat fully loaded, but that's not always the case.
If by chance you would discover that those tests were done with a light boat, and in spite of that they barely reached their rated max rpm, it wouldn't be so surprising that in anything less than those ideal conditions you can't see the max rpm anymore...

 

[Orange]

Re: Slightly o/t, but somewhat related

Well, it's a bit technical, but in a nutshell every manufacturer of marine engines require an initial sea trial.....

Very interesting thank you.

I didn't realise that every boat woudl be tested in this way, I assumed just one of each model range.

 

[MapisM]

TBH, I don't think that the procedure i mentioned earlier applies to EVERY boat.
I mean, it's safe to guess that Mercury don't ask SeaRay to test each and every 3.0 engine+outdrive package that they install on their 19' bowriders, before validating their warranty...
And of course, there are much more engine-related details that actually depend on the boat builder with inboard+shafts construction (exhaust design, shaft alignment, raw water circuit, etc.), compared to engines+outdrives sold as a package - not to mention outboards!
Fwiw, for all the engines fitted in the 50' to 60' f/b boats I considered (Cat, VP, MAN, MTU, all within the 700 to 1000hp range, and all either on straight shafts or V-drive), the initial test was a standard routine. And I know for sure that this is true also for bigger boats - not surprisingly.
But don't ask me to draw the line between the boats "individually tested" or not, because if there is one, I'm afraid I don't know where it is...
Probably our resident engines gurus know better, if anyone is reading this and would like to comment.

 

[Portofino]

I,ll revise by guess from SL62 ( on another post ) to this .Bow anchor drain and blue strip -

It's got all the MAN tickets in the service book --well broker says so ?

 

[MapisM]

I,ll revise by guess from SL62

Well, that's an easy revision, after I specifically said that I ruled out the SL62 and the VZ18!
...though strictly because of their size, a tad larger than myself and swmbo wanted.
If we were interested to go as big as 19m, they would have been our top choice for sure.

Nice find, that DP!
She was one of the boats right at the top of our short list, pity that you didn't point her to me earlier...

Though ref service book, most brokers are not even aware that such thing as the initial test report exists.
When they mention service, it's normally the maintenance invoices that they have in mind.
Which of course are good to have anyway - still more relevant than the VAT invoice, in my books...

 

[jfm]

MapisM, not ignoring you and I have all the data for my boat except I don't have the g'box ratio to hand, and without that the data is useless. I'm on the boat tmrw and will try to remember

 

[MapisM]

MapisM, not ignoring you and I have all the data for my boat except I don't have the g'box ratio to hand, and without that the data is useless. I'm on the boat tmrw and will try to remember

Thanks in advance J, but no worries if you'll have any better ways to use your time - 'twas just a curiosity, as I said.
Meanwhile, just to add the numbers I calculated based on the initial engines test, the boat I'm soon going to seatrial had a 12% slip at full load, with 31" pitch/28" dia props.
Well under the 78' mark of course, but still firmly in the P f/b category, with her 30+ kts max speed.
I'll be able to tell shortly how she performs now, 13 years after that first test!