The irony of hitting the new topic button is noted - repower

Dbillitto · Joined: 24 Jun 2004 Posts: 14

I know this has been discussed many times but ifnyou could look at it from another vantage point it would be much appreciated. I am the proud partner to Wishbone a 22. She is a 1994 and still has the original power (90 hp yamaha) that failed crossing a narrow section of the gulf between marathon and shark river inlet. I have been putting this repower off but want to get on mu way w it. My problem is that i use wishbone a couple different ways including pleasure cruiser, weekender but also to access an island off of NC to surf. I have always been able to push the limit of her draft and get in before skiffs, etc. Comfortable in 5 inches on plane and the occasional sludge that goes along w going in early. I am most concerned with keeping her draft as skinny as possible. Current engine weighs 230ish. Etec and suzuki is 330ish and yamaha is 365ish for a ninety. Boat is rated to 110. W 90 yamaha on it tops 33 34 mph on the speed.

Any thoughts on weight and draft. I have 2 batteries that are in the boxes on either side of the engine so i guess those could be moved forward? I honestly have information paralysis right now because everyone u speak to has an opinion on brands. Was going to repower w suzuki 90 at 10,125 installed. Any deals out there in the southeast. Long shot but does anyone have a 90 uamaha 2 stroke for sale?

Mainly, how has repowering affected draft????

Dave and Wishbone
www.suitesonfront.com

Foggy · Posted: Mon Jul 06, 2015 8:46 am Post subject:

Consider a jet drive OB or an airboat.

Aye.

Aurelia · Posted: Mon Jul 06, 2015 11:52 am Post subject:

Never went that skinny on purpose but I would agree that weight is a big factor in draft even on plane. You have already noticed that the current 90hp offerings don't come very close to the weight of the older two stroke.

The closest you can get in weight is likely with the current Yamaha 70 which is a high revving smaller block unit that actually runs a bit more like a two stroke in my opinion. You would be down on power perhaps a little but the weight is about even. Using a lower than normal pitch prop could still give you decent performance for light to moderate loads, but it would limit your top speed to the 25-30mph range (guessing). There is an older cruiser in Alaska that is running that motor and he has found the prop to be the biggest factor to get correct. Moving batteries or other weight forward would help as well and is not a hard thing to do with the space available in a 22.

If you think going even faster is an option that would help your type of shallow running then going up to some of the newest lighter 115hp units like the new Yamaha at 377lbs may be another direction for you.

Different waters down there,

Greg

nordicstallion · Posted: Mon Jul 06, 2015 3:44 pm Post subject:

No help here on repower & weight! My only comment is.... 5" on plane??? Change ur user name to BigBalls or Justplainnuts!!

Dbillitto · Joined: 24 Jun 2004 Posts: 14

I know it sounds skinny but when you get to surf on an island solo, well, one tends to take chances. I can tell you that i have on many occasions been followed by a skiff on to have the skiff run aground. Go figure but the boat runs skinny and if you happen to hit....hop out of boat and push out....easy peazy.

Any engine support is appreciated.

Dave

Sunbeam · Posted: Mon Jul 06, 2015 5:21 pm Post subject:

I was thinking along the same lines as Aurelia. The Yamaha 70 is really light, at 257#. It does have a smaller block (something around 1000cc as opposed to more like 1500cc for a typical 90hp), but if weight was key to me, and it fit my other usage criteria, I'd sure be looking at it.

Then too also as Aurelia said, if you need more horsepower, then the newly re-designed Yamaha 115 is light for the hp at 377#. I think that's only seven pounds more than their 90 (which is sort of "old" by now - I wish they would redesign that to fit logically in the line-up weight-wise, so I could re-power with something like a ~300# 90!)

What you're doing with your 22 sounds super fun Thumbs Up

thataway · Posted: Mon Jul 06, 2015 5:36 pm Post subject:

Folks you have to understand that Dbillitto is talking about hull draft, not running draft. I have a Suzuki 140 on my Caracal cat--and it can run less draft than a C Dory, because the single motor is in the water between the hulls. The distance from the top bottom of the antiventillation plate to the bottom of the skeg is 15 3/4" In a C Dory you run the bottom of the antiventillation plate about at the bottom of the boat--in his case about 5" below the water. So lets say that he is swinging a smaller prop on the old Yamaha, he may only have 14" of motor in the water. If he is really riding right on the surface of the water (which in reality does not happen until you get up in much faster speeds--he is still drawing 15 to 16" running depth--not 5". True the boat draft is only 5"--

The exception would be if he had a high rise jack plate, and low water nose cone pick up--and he might then run in 10 to 12" of water. But not 5".

Yes the Yahama 70 is the lightest at 270 lbs, BUT it is the same block as the 50 hp. We all know how the a 50 hp performs. The 70 will be developing the hp/torque at the higher RpM, and it may be fine, But you will be running it faster, more wear, and perhaps a little less longevity. (Note that the 50 and 60 are 6000 WOT, and the 70 is 6300 WOT. Notice that the 90 Yahama is 600 cc more displacement! (over 1/3 more!).

If you move the batteries into the cabin, they should be changed over to AGM's. You could run with less fuel in the tanks. or even put a tank further forward in the cockpit.

Your lightest 90 is going to be the Evinrude--and these are also lower displacement (as the 2 strokes tend to be).

So, if you really want the lightest 90 hp--then go with the Evinrude. The reports are good on them--but any one of the engines can fail at any time..

Aurelia · Posted: Mon Jul 06, 2015 11:19 pm Post subject:

I was reading 5 inches of clearance and not 5 overall. I tried 6 overall once in the 25 and the boat did just barely float but it made motoring really hard!

Weight is critical at a C-dory's relatively low speeds but that motor needs what it needs. I have never tried planing with the motor tilted up too severely but I think you could gain some significant clearance with trim alone.

Greg

Dbillitto · Joined: 24 Jun 2004 Posts: 14

Not sure about the debate on draft but the boat regularly goes into 6 inches of water. Have had 2 13 whalers and montauk and the C-Dory is so much easier in the shallows. That being said, i know the area well and go in on plane w a bit of scoot and runs at effectively half prop depth or near that. However, i think it is just as skinny if the engine is pulled up and you are poleing or out pushing especially w weighted or person on bow. My 90 yamaha has anti cavitation or ventilation or dolfin tail. I am gathering by the response that i should not expect near the performance (if draft is a measure of performance???) from newer engines.

That yamaha has been reasonably good to us. It has brought me to Florida twice including the keys which is a good ways. We have had the boat for 8 years.

Yamaha website shows it as still available but am thinking is government and export only sales. If anyone knows how to find a new one, well, you know.

Thank you for the info and the information paralysis is got me deciding between the suzuki, evinrude and putting a new powerhead on the yamaha. Isnt it time yamaha make a 325 lb 4 stroke?

Thanks much for the info, debate, banter. If you all find yourself in NC say "hello"

Dave