I want to build a diesel powered boat to haul people to my island hotel. It’s an hour and 45 min trip each way. 365 days a year. The boat we have now we bought used and it holds 40 passengers. And when we bought it had a pair of 200hp Yamaha outboards. The boat ran 29 mph with the engines turning 5400 rpm. Looking at a pair of yanmar 250hp 4cyl turbo diesels and arneson six drives. Waiting for the yanmar dealer to tell me what ratio transmission to spec with the engines and what diameter and pitch prop for the asd #6s. Called twin disc which I guess now owns arneson. The application dept is who I have to speak to and they cant be called only emailed. It’s been a day and a half since I asked them the tq handling capacity of the sixes. So no idea when I will receive a reply From then. So reaching out to oso bros.
. The 250 yanmars make 342ft lbs of torque. The boat is 42ft and holds 40 passengers and baggage in the bow compartment should I shoot for the same prop speed that the Yamaha 200s ran. They ran a small 15 pitch prop. That boat currently has a pair of Yamaha 300s and runs a 19pitch prop.
i think running outboards is retarded. They are shot at 2200-2400 rpms and not worth much to sell the puke lower units often as they are so heavily loaded. Plus the fuel saving is huge. The yanmar as supposed to consume 4.9 gph per engine at cruise which I assume is 3200 rpm which is 85% of max rpm of 3800. So apprx 40 gallons round trip. Current boat burns 130 per round trip when full up. Thank in advance for any info, RM

ASD 6 limits for diesel is 290hp/ 650 ft/lbs torque....ASD 8's are 380hp/1200ft/lb for comparison in a diesel

https://twindisc.com/wp-content/uplo...eson_Specs.pdf

do you have a link to your resort

On an application you've described, I'd look at a Simplicity Marine Drive. Not surface piercing, dirt simple, reasonably priced? We used them on Parasail and tour boats for years. Mated to 502's. Yanmar 315's, Cummins 6bt's. Talked to the manufacturer recently. Still available. Good luck!!!

thanks

Thanks for the info. I will contact them. Any idea what a pair of those drives costs today? Thanks again, RM

Looks like he missed your post.
i believe

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Simplicity drives are about 12k per side. Fiberglass swim platform is integrated into the unit. Whole assembly bolts to transom.

must be a hopping place, no posts on insta and the facebook page is gone.