how fast is your rib?

[Oscarguitar]

Saw 44, didn't see the units, didn't see the boat didn't see the engine.

[Courageous]

Well I paused the vid several times before I got it lads but it was deffo 44.5 kts!

[C-NUMB]

Originally Posted by willk

Bjoern

I

48 knots on a SR4 with a Yammie 50 is Guinness Book of Records material - the upper end reported for this rig (on here) is below 40kts, mid 30's being typical. There's not much SR4 left in the water at 35kts. I guess that explains some of the replies you've got/are going to get.

Fully agree.. only mono hull I know that is going close to 50 with a standard engine is the V-50 offshore boats. They have nose-cones for cooling water, prop axle is only 20mm bellow the bottom, and they use racing chopper or cleaver propellers. Not even all of these boat do 48...

here one

http://www.youtube.com/watch?v=jwMhv...eature=related

I don't say its not possible to do 48 in a SR4, i just have hard to believe its possible with a standard 50 outboard, not even with a racing prop on, as aerodynamics is so much poorer than in the V-50 boats. Engine might be tuned or then the output is much more than 50.

As far as i know 2 strokes Yamies have not been sold in USA for a long time, at least not for private use?

[rocknrolla]

many things are possible but i think u have got more chance of fineding a hand break on a conoe

[kubcat]

Originally Posted by spartacus

Just what I thought.

1 boat - okay, but that's it
2 boats - where am I supposed to park the bl**dy car?
3 boats - your dinner's in the dog (again)
4 boats - someone from the council called to see if you were trading?
5 boats - someone from the Royal Navy called...
6 boats - see you in court!

In all fairness 3 are allocated one each to my boys. But then there are a few hardboats which we will not talk about.

[kubcat]

Originally Posted by kubcat

Love this thread and want to contribute but I have never been concerned with the actual speed number. I just love the feeling of speed, but in the interests of research I will be quantifying the fleet.

Over the next few weeks plan on taking all the family's RIB's and SIB out for a run with the iPhone gps app. Of course that depends on weather and other commitments.

Anybody wants to take a guess beforehand, you are most welcome.

Zodiac AR340 with a beat up 2001 Yamaha 20hp 2 stroke. Prop came with outboard and i think is 9 7/8 x 11 1/8.

Dockitjet 5.6m with 1996 200hp Suzuki in excellent condition. Has a 3 blade 25 inch prop at the moment. Only ever been run once and bad chime walk at 3000rpm but will raise the motor, put a 4 blader on and some weight in the front to see what will happen.

Ribtec 890SX with twin Yamaha diesel sterndrives 240hp ME421 sti's. Currently had standard Yamaha 21 inch props.

3.2 m no name air floor, inflatable keel Chinese SIB with Mariner 1989 15hp. Not sure of the prop, the only thing i can see on it is A122105P.

Redback Stinger 2.9m rib with Mariner 9.9, about 1990. No idea of the prop.

Zodiac 470 with (2000?) Mercury 50hp. Has a stainless 18 pitch prop.

Okay, the Ribtec 890SX with twin Yamaha diesel sterndrives 240hp ME421 sti's hit 58mph / 78kmh today.

[Poly]

Originally Posted by Searider

That looks impressive - was that 44 point something?

The biggest number in the video seemed to be 45.3; but that was only momentarily so it might be partially due to GPS error rather than absolute speed; it was consistently reading > 43...

Was there any current and did you run the other way as well?

[TBone]

My wife and I hit 72mph with ours, a Caribe MVP-10, mercury 15hp 2 stroke. Its usually alot slower when Im not ripping up Rt. 95 with it dragging behind the truck.

[r4e]

WOT 49+ knots in calm seas, zero chine walk what-so-ever. Ballistic 7.8 with 2x150 hp Evinrude Ficht RAM, five tanks of diving gear and 400 liters of gas.

If the sea conditions allow it, my "cruise" speed is 45, just for the fun. Sometimes 30-40 knots with more waves and a hard ride. However, unless I manage to ride the tops of the waves I have to drop to a slow 20.

[jyasaki]

Originally Posted by r4e

WOT 49+ knots in calm seas, zero chine walk what-so-ever. Ballistic 7.8 with 2x150 hp Evinrude Ficht RAM, five tanks of diving gear and 400 liters of gas.

Out of curiosity, what's your fuel consumption at that speed?

jky

[r4e]

Originally Posted by jyasaki

Out of curiosity, what's your fuel consumption at that speed?

Fuel consumption at max revs is about 1.2 liters per nautical mile per outboard, i.e. total 2.4 liters per nautical mile or about 120 liters/h or 2 liters per minute. Or 31.7 gallons per hour. The tanks can hold four hours of gas at max speed.

However, if you compare this to the minimum consumption soon after planing speed, about 0.95 liters per nm per outboard, the difference is not so big that I would select the speed by economy only.

It makes it easier for me to justify all the maintenance costs if I manage to spend more on gas (=enjoying the boat) than on maintenance. I've had one transmission replaced completely, all the hypalon pontoons replaced (custom made) and the electrical systems rewired. Plus added side scan sonar and other goodies. That's a lot of gas to burn yet;-)

[jyasaki]

Originally Posted by r4e

Fuel consumption at max revs is about 1.2 liters per nautical mile per outboard, i.e. total 2.4 liters per nautical mile or about 120 liters/h or 2 liters per minute. Or 31.7 gallons per hour. The tanks can hold four hours of gas at max speed.

Thanks. Just curiosity driving that question.

jky

[khalidow]

thaks to all the help regards to my post plane off problems, i officially lowered outboard made some spacers so motor has more tilting angle. i officially get about 57mph with 4 crew onboard vessel with my 5m duck and mercury 225hp no chine walking nothing, drives like a dream. rev gauge doesn't work some wiring issue but will keep u posted

not that i need to go any faster is that weak for a 1980's 225hp
or am i suppose to get more power from it?

[Hysucat]

Mmmm .... is that all, I was just getting into it.

This was a standard boat and engines, the only modifications were the gearboxes and props.

8m Hysucat - 2x 200 Mercury's (Standard), bullet nose racing gearboxes, low level water pickups, surface piercing props.

74knots / 85mph / 137kmph on final day of testing. Pretty sure it can make 80knots with jack plates on the transom.

Hysucat 8m adrenalin waverunner in Struisbaai - YouTube

Hysucraft - Evolution Evolved. - Official Website - Designers & Developers of Hydrofoil Assisted Craft.8m RIB

I guess Cooke still beats me with his Malcolm Cambell setup

[Cookee]

We weren't using a surface piercing prop at all - in fact the record run was with a modified Raker. The best set up we had which was on Coniston was a Mercury 280EFI ROS 15" with a modified Sportmaster. If you need a bit of bow lift use a Raker, a surface piercing prop will lift the stern if anything.

[Hysucat]

Originally Posted by Cookee

We weren't using a surface piercing prop at all - in fact the record run was with a modified Raker. The best set up we had which was on Coniston was a Mercury 280EFI ROS 15" with a modified Sportmaster. If you need a bit of bow lift use a Raker, a surface piercing prop will lift the stern if anything.

Hi Cookee, the front and rear hydrofoils do the job of getting the boat out the water. With my ideal setup the idea we have to get as much of the boat and engine out the water. This boat hit the wall at 5000rpm, nowhere near the 6200 limit. Getting the engine further out the water will have it kicking up a nice rooster tail and manage to get full revs.

[HCD Canada]

50.8 MPH on a Aquarius aqua cat 18 pitch cleaver

[Cookee]

Originally Posted by Hysucat

Hi Cookee, the front and rear hydrofoils do the job of getting the boat out the water. With my ideal setup the idea we have to get as much of the boat and engine out the water. This boat hit the wall at 5000rpm, nowhere near the 6200 limit. Getting the engine further out the water will have it kicking up a nice rooster tail and manage to get full revs.

You just need a smaller pitch prop - smaller diameter can have the effect of increasing revs and speed but it depends on how high you're running the prop and other factors.

[blueboy758]

Compared to some speeds here I think my boat and engine are broke.... 5.3 offshore fairly wide 115 ficht about 40 on a good day three up and 50 ltrs of juice.

[AK2AZ]

5.3m Zodiac Pro Hurricane
60 gallons of fuel
115 2-stroke Mercury
4-blade prop
500# misc. gear w/2persons
40mph @ 5,250rpm burn rate 5/gal. hr
...not propped for speed as it chine-walks over 43mph.