Repowering a ShartCat 23

[PNG YFT]

Hi

After lurking around this board for a while, the time has come to post a query.

I currently have a Shark Cat 23 with two x 225 1998 Evinrude two strokes. As you can imagine, the price of fuel and declining reliability of the Evinrudes has finally forced the decision to repower with four strokes.

Have pretty well decided on a pair of Suzuki DF140s. Can any one give some idea of likely performance differences with dropping down to lower powered outboards? Top speed isn't the main criteria.

Would also appreciate any suggestions on prop sizing.

Thanks in advance

[boatboy50]

Hey PNG,

You will notice a huge drop in top end speed between that change.

My advice would be to not go any lower than 150 Suzukis, and even better would be the 175 Suzukis, which are the same engines, but with variable valve timing.

Well worth the extra money.

PM Julian, as he has a smaller cat with these motors (see it in the for sale section), and will give you a better idea.

Regards

Darren

[sharkcat one]

Hi

After lurking around this board for a while, the time has come to post a query.

I currently have a Shark Cat 23 with two x 225 1998 Evinrude two strokes. As you can imagine, the price of fuel and declining reliability of the Evinrudes has finally forced the decision to repower with four strokes.

Have pretty well decided on a pair of Suzuki DF140s. Can any one give some idea of likely performance differences with dropping down to lower powered outboards? Top speed isn't the main criteria.

Would also appreciate any suggestions on prop sizing.

Thanks in advance

HI GUYS,
I HAVE A SHARK CAT 23, IT IS POWERED BY 2 X 200HP YAMYS

YOU HAVE TO REMEMBER THAT THESE BOATS WERE BUILT ALONG TIME AGO
USEING OUT DATED MATERIALS AND TEC. THESE BOATS ARE BUILT HEAVYER
THAN THE CATS OF TODAY. I WOULD NOT GO UNDER 175hp ENGINES,
EVEN GOING TO 15Ohp YOU WILL BE DISAPOINTED .

TO GET BETTER PERFORMANCE FROM YOUR BOAT TRY DOING WHAT I DID--

CUT ENGINE WELLS OUT AND BLANK IN TRANSOM THEN PUT ENGINES ON PODS,
WITH SMALL PLATFORM BETWEEN PODS.

SEE YA

[Dean1]

Hey PNG,

You will notice a huge drop in top end speed between that change.

My advice would be to not go any lower than 150 Suzukis, and even better would be the 175 Suzukis, which are the same engines, but with variable valve timing.

Well worth the extra money.

PM Julian, as he has a smaller cat with these motors (see it in the for sale section), and will give you a better idea.

Regards

Darren

Hi Darren is that a pic of a seafarer in your avatar?

[boatboy50]

Hi Darren is that a pic of a seafarer in your avatar?

Certainly is Deano,

Need a fill in boat for a while, so a Seafarer will have to do!

[cormorant]

They should be a really relaible motor if looked after and not huge hours. If they are solid motors be worth giving them a freshen up as fuels expensive but motors are $$$$$$. 225's on 23 are a weapon.

Beware of too much weight of some newer motors on the Shark.

Smaller motors will work in a higher rev range and won't return as good as fuelnubers on the shark. Be better of running your current ones at half throttle and having lts in reserve if you need it to get home.

[Noelm]

been in lots of 23's with various power, you need to consider what sort of max weight you may have at some time, if it is just a straight fishing boat, then smaller HP can be considered, been in one with 115's and even though it was no speed demon, propped correctly, it was OK, so I guess 140HP will be adequate as long as you are not going to be loaded to the hilt at times, I worked out of one that regularly carried over 2 tonnes of added weight, and even with over 200HP a side it was still just enough, but light, it would fly!

[PNG YFT]

Hi Noel

Pretty well used exclusively for fishing with a 20-40km trip out and then a day's trolling. 300l fuel, 3 or 4 anglers and associated kit, so pretty lightly loaded for a 23.

One of the things I like about the 140 is the weight - she is already a bit heavy at the back so wouldn't want much more sitting back there (boat has pods). Not overly concerned about top speed as I cruise at around 22kn at the moment.

Anyone have any ideas on a starting point for propping? I am leaning to the 14 x 22's, but would appreciate any input. Will definitely have counter rotation - if that makes a difference to prop sizing.

Thanks

[julian1]

i would go the 150's, they are like chalk and chees compared to the 140's. the 140's feel like a 115 but with alot more top end. your fuel consumption would be similar with the 150's as they would be working far less. even better Suzuki 175's with VVti for extra torque. The Yammie 150 4 stroke is also a very strong engine and these will be light enough for the 23 as they would be simialr or lighter than your current engines.

[boatboy50]

Hey,

Having been in one with 140 Suzuki's, lightly loaded, I can tell you you will be regretting powering it by 140 Zuks.

I would definately opt for a 150 or 175. I have nothing against 140 Zuks, just not on that package. They are a great engine.

The 150/175 Suzuki will still be lighter than your current 225's I would think.

The 140 Zuk is light in weight, and also light in cubes. Think about it carefully.

Regards

Darren

[Noelm]

hhmm seeing as you have pods, then it must be a later model (if original pods that is) so any weight savings are going to be a bonus, I guess maybe some old fashioned research and forget the brand and operating principal for a bit and just find out what Motor is lightest in the 140 to (say) 175 HP range, then start to narrow down the choices from there, Boatpoint has a good section on motor comparisons that seem to be fairly unbiased (most times) so that might be a starting point.