repowering question

[DonV]

To all,

Here's a copy/paste of a private forum conversation with a 23' Cobia/Pathfinder owner's results with his four stroke 300 hp Yamaha. I had asked him his performance because of the similar size of his boat to the SeaCraft. Let me tell you, his boat is one step above real nice!!!!


"After break in, I was swinging a 21 Yam SWS-II 3 blade.. Was a little tall, and only hit 5800 rpm light. It was square, meaning 3500 rpm was 35 mph (and 4.1mpg) and 5800 was 58 mph. But, I didn't want to load the boat and lug the motor. The 19 pitch hits 6000 rpm, but loses some speed and economy.. It s the best prop, and with the SDS, shifts silently.. Very cool to have a silent boat around a pod of Sails or Dolphin !

Numbers with a standard load and the 19 pitch prop:
Like all boats, there is a best-economy rpm, which is 3300, 29mph, @ 3.8 mpg. The 'Happy' rpm is 3900 at 35mph @ 3.2 mpg. WOT is 6000/55 mph @ 2.0 mpg. These numbers are in a light chop.

We spent 9 days in the Keys this July. We filled the boat up and fished, ran offshore, trolled some, spearfished out by the reef and buzzed around with the girls.. We burned a total of 71 gals and ran 230 miles. Total trip avg of 3.2 mpg.

The F300 is strong, quiet and a good example of why you max the HP on an offshore boat. I think it would be an excellent repower for the 23 Seacraft.. Even the F250 Offshore would be excellent, and maybe less money. The older F-250B's are rock solid motors as well. Depends what $ you have to spend.

One note.. I would measure the cut transom width and check the swing of the steering on the engine cowls. There was one model with a pretty small cutout.."


Still, if it's me and looking at the $2,000 to $3,000 difference with the 250 eTec versus the Yamaha......I'd go with the eTec.