Could someone explain this please?
 

New Powerboat has a test of a 29 Fever with twin 320hp 6.2's and compares it with a 29 they tested a year or so ago with a single 550hp 525sci. How can the 640 hp boat be 13 mph slower than the 550 hp boat? Does the weight of that second engine make that much of a difference? If so I'm going to diet my ass off:D

Yes, it sounds like a weight and drag coefficient issue, but I think you'll like the drivability and handling of a twin engine application better. :)

Mark/KAAMA

Perhaps different x dim, props, fuel load, testing conditions.

Don't forget the added drag of a second lower unit and prop.

Jon

Yea, weight and drag kills you everytime. I always wondered why someone didnt put a single #6 in a boat and 2 or 3 engine in a line like a tracter puller.

Bucky - I read your question and wondered the same thing, I have a Baja 29 Outlaw with a single 502 mag 415 hp, I bought it about 3 months ago and everyone told me the boat would be a dog. I'm not a genuine speed demon like a lot of people on this website, so I bought the boat anyway despite what everyone said. I spend most of my boating time drinking beer tied up to other boaters in coves at LOTO. I have only taken it out 2 times prior to winterizing and I have not burried the throttle yet, but I was very surprised at the power it does have. It cruises easily at 50 mph on gps and the throttle is only halfway down. I'm anxious until next spring so I can see what it will do. I think the drag of an extra lower unit and the weight is definately an issue. I know a guy that has the same boat with a single 500hp and he says it will push 70 mph. Fountains are nice boats, they are made to go fast, my buddy has a 27 fever with a 502 mag in it and it hauls. I imagine a 29 Fountain single engine 502 mag will move pretty good also. Big E

Kinda like the difference between a 31 foot boat and a 35 foot boat with same power (twins)...I think the 35 will be faster because of the better weight distribution and leveling the boat so it doesn't plow in the water draggin azz....MHO....Geeter

Geeter-B - I see you are from St. Louis, I am too. Do you boat at LOTO? BIG E

Arneson reports speed increases of 10mph are not uncommon on boats with efficient hulls.

That 10mph is gained by doing nothing but losing underwater drag.

A twin has DOUBLE the underwater drag.
And another 800 pounds on the tail.

The numbers on the big HP single versus a medium HP twin sound pretty ok to me.

One of the boat mags did a similar story years ago on the 29 Fountain; one with twin 260 small blocks, the other with a single 525SC. The single engine boat was 10 mph faster.

It makes sense. The twin engine/drive package weighed 2400 lbs and the single engine/drive package weighed 1400 lbs. Anytime you can take 1000 lbs out of a boat and keep almost as much HP (490 PHP vs. 2 X 260 PHP) you are going to go faster. Then there's the drag. From an article on the Blackhawk drive when it was introduced, a Mercury engineer was quoted as saying a Bravo drive creates 350 lbs of drag when pulled through the water at 60 mph. An Alpha drive likely isn't as bad since it isn't as big a gearcase, but two of them will definitely create more drag than a single Bravo.

By the way, the article also said that the Blackhawk drive created only about 10% of the Bravo's drag. So what I want to know is did they ever test this boat with single or twin Blackhawks?

What kind of numbers did that special edition 29 Scarab with twin small blocks and Blackhawks drives produce?