Scorpion 8.5m Performance

[Paul E]

I've recently bought a 2005 Scorpion 8.5m. Originally it came with an F250 Yamaha, it was upgraded to an F300 Yamaha in 2012, and I've just ordered a new F350 V6 Yamaha on trade-in which will be here any day.

I'm curious about performance figures that people have experienced with the 8.5. The antifouling is an absolute mess right now and needs stripping right back to gelcoat to start again. It was kept on a dry dock for years before the previous owner to me bought it at the beginning of spring, subsequently it's been in the water since without a recoat, and a pressure wash has crumbled it and left the running surface like granite! This has meant I haven't been able to get representative top speed, cruising speed and fuel economy so far - although the max GPS speed is logged at 52 knots before I bought it (I'm just about reaching 40 currently with the drag). Despite this the ride quality, handling and build quality is absolutely incredible, I'm hopeful the 350 will push it comfortably over 50 knots with an efficient 35-40 knot cruise.

[gtflash]

40knots is definitely too slow. 52knots with a 300 is pretty good IMHO.

I had a 7.5 with 200hp that ran 47ish knots. Then a lightweight 8.1 twin step with 250ho that runs 57-64knots dependant on prop, top of my head figures. The stepped hull is a fast boat and your boat will be slower and a lot heavier.

The 7.5 had awful anti foul. I tried everything DIY to get it off and in the end gave up, it was clean however.

Is the bottom clean and rough or dirty and rough. How many revs are you at when topping out? Is there any trapped water in hull <common problem>. Have you got a full fuel tank and are you carrying excess baggage? I'd look for trapped water first, the rough bottom probably doesn't do much to speed. My hull is copper coated and then rubbed up with sand paper to make it slightly rougher!!

[Paul E]

Thanks for the reply. It's got a couple of months worth of slime on it, but its incredibly rough - years and years worth of crumbling re-coats. Properly awful! No real difference between freshly pressure washed and now with the end of season growth. I'm going to have it blasted with a very fine media and start again with Gelshield and Interspeed 300.

I suspect there may be a bit of water trapped as she lists slightly to starboard when moored, I'll blast out all of the rigging tubes and drains etc when I haul it out in a week or two. Currently with a full tank of fuel, but only a couple of knots difference between full and empty. RPM is around 54-5500, which is too low. Prop I think is a 19p 4 blade that I'm not convinced is a great fit for the boat.

My last boat was a splashed Ballistic 7.8 with a 250HO G2, that would run 53-54 knots with a light load and a clean arse, GPS max of 58 with a few knots of tide helping! I know the Ballistic is an intrinsically faster hull, but the ride of the Scorpion is so so much better (and I didn't think the old one was bad!).

Stepped 8.1 sounds like an awesome piece of kit! I did a good few years racing Class 3A/B offshore boats, I had a Phantom 19 with steps (made with a plug in the genuine P19 moulds, designed by a good friend of mine that worked a lot with Lorne Campbell who I believe would have done the Scorpion step design), and it was an absolute weapon. Ran 75mph on Coniston during Records Week with a bone stock 115HO Etec (only gearbox shape was modified and solid mounts fitted) and solid low 70s in race trim. I've got a lot of experience with props & height etc and have a great relationship with the local Yamaha dealer so I'm really looking forward to getting it dialled in.

[gtflash]

Hi Paul.

I remember, you used to post some great videos I believe. Did I buy some solid mounts off you or get contact details for the?. (Still in my garage)

I bet the prop and engine is setup leisurely. But you will be able to nail that with a new motor. Trapped water is common in cable trays and hollow cavities such as under deck bilge.

With non stepped hull scorpion I tried several different props including high 5, bravo, trophy, rev4, laser2. The rev4 seemed to fit the hull very well and also works on my stepped hull version. Good grip and good top end.

They aren't the fastest hull, but you get great ride comfort. I have spoken to Lorne Campbell via email a few times about my boat, he remembered all the history and gave me some great advise on the merits and limitations of the hull. It's a lovely hull, the ride always impresses other people.