Originally Posted by HUMBER P4VWL
Our 5.4 chine walked with a 90 optimax.
What is the max power the transom will take? Also, weight.
The 90 Optimax weighs 170 kg. That's a heavy engine !
The SR4.7 is specified for 70 HP and around 130 KG engine. However i'm not so worried about the extra 15 kg, i anyway put 500 kg of people and diving equipment in also (100kg diving-tanks right next to the transsom). That also why the 90 HP would be nice (to get on the plane)
The only issue could be when it's empty going full speed, but i never do that for waterskiing, diving or fishing purposes.
The businesscase for changing engine is not good enough if i only look at the savings on full ect.. I need something more, and since it's currently underpowered for my use, i was thinking to add enough power to avoid comming to that conclusion again.
with a 90 HP E-tec i think the boat would accomodate 4 divers with twin tanks and stage bootles, maybe even a driver. 4 divers with twin tanks can just barely get on the plane with the 65HP. It doesn't leave much flexibility when the waves are rising, or even if some divers are the heavy duty type (+90 kg).
I know the obvious answer would be to buy a bigger boat, but then everything else gets bigger as well. Bigger trailer, garage, car, fuelconsumption, ensurance, and last but not least PRICE......
I understand the point about chine walking, but it only happens if you go high/max speed, right ?
The SR have a quite narrow and steap hull, so i my oppinion it needs relatively large engine not to be underpowered. With enough power the water ballast system would actually be usefull also. At the moment i have closed the hull on my boat.