Its raining, so no sailing -- so I did some "google research" and it seems the new (since about 2008) 9.9high thrust is 212cc.and weighs 47kg.
Some research on the "wayback machine" found the
US Yamaha website archive from 2005 and it shows that the 20hp Yamaha was 323cc, as was the 9.9hp in both standard thrust and high thrust.
(if you want to look around these old websites, use the "site map" to get to the outboard data as some of the tabs do not work). -- So presumably, at that time, there was the possibility that the 9.9 could be "up powered" by changing the carburettor / jets. - it also make me think those old "323cc" 9.9 high thrusts were being run quite light?
I think 2006 was when I bought my F20, which was then a new, lighter and physically smaller engine design, with a (then) new 362cc engine. I recall I was expecting it would fit a lot better than the older (and larger) 9.9 and I was expecting they would update the 9.9 in a few years to the new 362cc engine and I could then just change the lower gearbox to get a High Thrust version. - Of course this did not happen.
As far as I can tell, around 2007 /2008 they must have sold off the last "323cc" 9.9 's as they introduced the new 212cc 9.9 hp (and also a new 8hp 212cc).. At this time the F15 and F20 were still 362cc, same as mine. (Jan 07 still shows the old model, but
Feb 2008 shows the 9.9 high thrust as "new" 212cc).
The current situation is that the F15 is still 362cc, but the F20 and F25 are now 432cc !.. Presumably this is a way to sell off the old 362cc engine blocks??
I suspect its quite possible that they learned from people buying the smaller engines and changing the carbs. So they now make the "paired" engines very close together in power (9.9hp & 8hp 20hp & 25hp etc)
It looks like the current 9.9 high thrust is quite a different beast (at least since 2008!) from the one we probably have club members recollections of.? Does anyone have the new 212cc high thrust?
I still think that a slowly turning ("high thrust") large prop will be much better for the cat than a fast spinning one. Also, not much has changed about the hydrodynamics, so we still cannot exceed our hull speeds, and Peter's experience with two small outboards of total 10hp does seem to confirm that a Catalac 8/9 needs about 9 hp or less for general motoring.
I suppose if you are motoring into a gale, you will need a lot more thrust, and I may do some calculations if I get bored! I think I might be able to extrapolate some data from my original 2012 prop test results..
Bob also pointed me to the "electric" Catalac on the facebook pages.. A quick calculation shows that he is running each of his two electric drives going out of the marina run at only 2.4kw (presumably each). This is roughly equivalent to 3hp each!. But this again suggests that a big prop is what is needed, and that only relatively modest actual hp is actually needed in most conditions.
I have a
Spirit 1.0 electric O/B arriving soon that is really for the dinghy, but I will try and fit it on the boat to see how it performs.. Should be an interesting experiment!
Comments