out board size for cats

[44'cruisingcat]

Sean, a 44C powered by Honda 20's is being launched on Sunday, so I should be able to get some good info about how it goes.

[northerncat]

cool that would be great, of most interest is how well the hondas pull it up in reverse, whether there redirected exhaust gas flow actually works
sean

[northerncat]

how are those hondas going 44c?
sean

[northerncat]

yamaha are replacing the 323cc 9.9 high thrust with a 212 cc 9.9 high thrust, i cant see this is a good thing and rang up my local dealer to ask why and he said the influx of chinese copies has had an impact on this so yamaha have changed the 9.9, not in good way to my thinking
sean

[viking69]

they are adding power tilt as an option on the new yamaha 9.9s highthrust so that would be cool.

[northerncat]

yes but power tilt doesnt do much for you when you are a 40ft cat punching into 30knots with 2m swell, theres just no substitute for cc's, why would you buy the 9.9 over the 8 when essentially they are the same thing?
sean

[Tropic Cat]

I'm still having a hard time with this thread. Anyone who sails a cruising cat knows what happens in moderate winds and any current at all. There is no substitue for power.

Also, in moderate head or following seas, any outboard cavitates. Add to that the difficulty of raising and lowering the engines, fuel economy and power generation. I think it's inescapable that inboards are the obvious choice.

Bu then again, I will admit that I'm definately biased.

[charlie p]

We have a PDQ32 with twin Yamaha 9.9 high thrust outboards. Displacement is 7200 lbs bare - more like 8500 lbs for out typical short cruises to date. A few observations about the engines:

I had always assumed we would get a boat with an inboard diesel, but when this boat came on the market, I decided to take an objective look at the gas outboard option. The choice was less obvious than I originally thought. Having used the boat for a year, including a trip down the Washington coast into an ugly south wind, I am satisfied with the outboards.

My concerns were the usual: Reliability, safety (gas), fuel economy, prop lifting, etc.

Reliability was my number one concern. There is no way an outboard will have the same reliability as a properly maintained diesel. The newer outboards are pretty good though, and with two engines, I actually think I'm better off than with a single diesel (i.e. what all cruising monohulls have) but obviously not up to the reliability of twin diesels.

Cooling system problems in salt water are a big problem. I plan to install a built in flushing system. Blocked cooling passages seem to be the number one cause of early failure for these engines when used in salt water. I also plan to add temperature gauges with alarms.

I think the safety problems with gas can be managed. Our fuel locker is separate from everything else and is vented at the bottom. The fuel line runs to the engines are short and well protected. Also, most cruisers must deal with gas anyway for their dinghy engine.

Fuel economy is worse than a diesel, but not horrible for four strokes. We often run only a single engine and back off a bit on speed, which really helps.

The prop lifting problem depends a lot on the boat design and engine location. Our boat is a center cockpit design with the engines about a third of the way forward on each side of the cockpit. We rarely experience over rev. I think that cats with outboards hanging off the back of the hulls are bad news.

One thing I really like about the outboards is that they can be hand started with a pull rope. We actually had to do this on a recent trip when a starter failed and it was quite easy. We both practiced the procedure - my 120 lb wife had no trouble hand starting the motor. Note that the motor will start and run even if the entire electrical system has failed. Make sure you have clearance for hand starting. The Seawind 1000, for example, has it's Yamaha 9.9's in deep wells which preclude a clean pull. The owner of KatieKat added a block to direct the pull upward and reports easy hand starting.

The raising/lowering thing is a bit of a pain but acceptable. The earlier comments about the latching mechanism are correct. It is a poor design. It sometimes fails to latch when the motor is lowered and if you then put it in reverse, watch out!. We now have a rule onboard about opening the engine well and double checking the latch after lowering the engines.

A PDQ36 owner recently replaced his 9.9's with the new high thrust 8's. He reports nearly the same performance and LOVES the electric tilt.

Charlie Phillips
Portland, OR

[northerncat]

i havent heard that cavitation has been a problem with cats in aus and theres a lot of them out there powered by outboards, theyre pretty cheap to compared to diesels
sean

[northerncat]

some good news from yamaha pasted on the easytalking forum
RE: Yamaha 9.9 DEX models
Yamaha have been kind enough to permit a few additional 9.9 DEX units to be built in Japan. The documented concerns of many (where our EASY designer played a key role) were vetted with the Yamaha hierarchy both here and overseas. We are happy to report that they paid the EASY sites (including the Forum) a visit, making the efforts of those submitting data, worth while – a big thank you to all.

These motors are to be built over the Christmas period, available late January early February and should carry 2008 dates. Unfortunately, the first shipment has already been allocated, however, if the numbers are there, they are willing to get a second shipment together (minimum of 10 motors per shipment). The first shipment took less than a day to sell. So…if you are in the market for this particular unit, it may pay to get in very early.

The contact person is Lawrie Hope in Australia (Wynnum Marine) on 07 3396 9777 or 0413 117 212 or call Peter Snell.

Before you do, Yamaha will require a non-refundable AUD $1000 deposit, the remainder due early 2008. The cost of the motors cannot be set until the final numbers are in. Having said that (and I am only guessing here) they a should be no more than AUD $4000 each, the first shipment came in under this figure.

[44'cruisingcat]

Originally Posted by rickm505

I'm still having a hard time with this thread. Anyone who sails a cruising cat knows what happens in moderate winds and any current at all. There is no substitue for power.

Also, in moderate head or following seas, any outboard cavitates. Add to that the difficulty of raising and lowering the engines, fuel economy and power generation. I think it's inescapable that inboards are the obvious choice.

Bu then again, I will admit that I'm definately biased.

As a last resort, in moderate winds you could always try the sails.

I regard the sails as my primary source of propulsion, not the motors. The motors are for maneouvering into and out of marina's etc, or for when there is almost no wind - when presumably there would be little or no sea state as well.

It is also possible to mount outboard so that they will "cavitate" (actually the propellor is ventilating, not cavitating) only very rarely,or not at all.

A pair of Honda 20 four stroke outboards weighs (and costs) considerably less than one 20 hp inboard diesel. This means the boat will sail better in light winds - so the motors will be used less.

[northerncat]

Originally Posted by rickm505

I'm still having a hard time with this thread. Anyone who sails a cruising cat knows what happens in moderate winds and any current at all. There is no substitue for power.

yes you go sailing

Originally Posted by rickm505

Also, in moderate head or following seas, any outboard cavitates. Add to that the difficulty of raising and lowering the engines, fuel economy and power generation. I think it's inescapable that inboards are the obvious choice.

Bu then again, I will admit that I'm definately biased.

for the price on one inboard you can have two out boards and the cost of one inboard buys an awful lot of petroland the fourstrokes arent duel guzzlers 15hp honda 2lp hr for 5knots cruise one motor, not to mention that petrol is cheaper than diesel, also its a lot easier to change out an outboard than an inboard and you have no secondary maintenance to under take ie sternglands etc etc. I think it's inescapable that outboards are the obvious choice.
sean

[Tropic Cat]

Originally Posted by northerncat

yes you go sailing

I think I've been misunderstood. Admittedly, I wrote that a bit too quickly last year. It looks like your mind is firmly made up, but I'm going to take one more shot at this. I am not attempting to argue the point.

In perfect weather those outboards will be just fine. My original point was that when the wind kicks up to 30+ knots, and wind driven waves top 5 meters, you'll need more engine power.

I think you are focusing on your boat's light weight as justification for 20hp outboards. I just don't see how you are accounting for the poor aerodynamics cats have. We offer much more wind resistance than you would think, at least double what the same length monohull has. There have already been a couple of posts in this thread that comment on cats motoring in high winds which illustrate the challenge.

Remember, when wind speed doubles the applied force on the boat doesn't go up in a linear fashion. Gord can give you the formula for this (I think force squares as wind speed doubles) but suffice it to say that when the wind speed doubles you are not pushing against double the original wind driven force. This force is in fact much higher. Engine power on the other hand is linear. You'll be at the mercy of high winds in any case but with much more of a chance with more HP.

Just my 2 cents worth as I'm not attempting to argue the point. It's just that I attempted to motor in 50 knot winds recently, and didn't get very far. If I were you I'd be looking for a couple of used diesels that need rebuilding. Possibly Yanmar 2GMs or 3GM's if they are cheap. Make it your summer project. You'll be very happy you did.