How much hp for 50-55 knop, in a revenger 27-29?

joakimhansson · 12 July 2006, 20:44

Diesel and outboards.

My guess is 250 hp outboard or 300 inboard (yanmar 315?) good guess?

And if you want to go 55-60 knop?

Hugh Jardon · 12 July 2006, 20:58

why dont you call revenger and ask them? they must know how their boats perform with the different engine options!

Quote:

Originally Posted by joakimhansson

Diesel and outboards.

My guess is 250 hp outboard or 300 inboard (yanmar 315?) good guess?

And if you want to go 55-60 knop?

joakimhansson · 12 July 2006, 21:20

Yes why do we use this forum when we can call/mail all manufactures when we have questions?

Someone else who have any answer on this question?

Hugh Jardon · 12 July 2006, 21:39

Quote:

Originally Posted by joakimhansson

Yes why do we use this forum when we can call/mail all manufactures when we have questions?

Someone else who have any answer on this question?

if you are serious about a revenger then you can ask all the engine questions you like and i would expect they would be able to give you the best advice, but just my opinion...if i was buying a revenger i would speak to them and get their input etc etc

but....i am not a consultant

danny · 12 July 2006, 22:10

Friend of mine did 53 knots on a 27 footer with 225 hp on her back.
Now he ordered a 300XS en hopes to make it over 60 knots.
I believe this engine will give 330 hp.

searafting.no · 13 July 2006, 09:20

We are rigging a Revenger 27 with a 250 Verado at the moment, it will be out on the water in about 2-3 weeks and we will give you some performance numbers, what we have seen is that mounting hight on the engine and the what prop you run will have influence on what speed you get, we have monted the verado's 15 cm over the keel and achived 56 knots with bravo one props and 61 knots with revelution 4 props on a revenger 34. (2 x 275 hp)

You could mount the verados pretty high on the transom and if the boat is built for a 25 inch leg, you could without any problems run 20 inch engine on the boat, lifting the engine gives less drag and more top speed.

We allso have tested a Revenger 29 w/stepp and 2 x 250 Suzukies with bravo one props, but there is no way we could lift that engine that much as the verado's, the suzukies starts cavitate when we lift the engiens more then 7-8 cm over the kell, = the suzukies gives more drag and lower speed

codprawn · 13 July 2006, 10:48

Quote:

Originally Posted by searafting.no

We are rigging a Revenger 27 with a 250 Verado at the moment, it will be out on the water in about 2-3 weeks and we will give you some performance numbers, what we have seen is that mounting hight on the engine and the what prop you run will have influence on what speed you get, we have monted the verado's 15 cm over the keel and achived 56 knots with bravo one props and 61 knots with revelution 4 props on a revenger 34. (2 x 275 hp)

You could mount the verados pretty high on the transom and if the boat is built for a 25 inch leg, you could without any problems run 20 inch engine on the boat, lifting the engine gives less drag and more top speed.

We allso have tested a Revenger 29 w/stepp and 2 x 250 Suzukies with bravo one props, but there is no way we could lift that engine that much as the verado's, the suzukies starts cavitate when we lift the engiens more then 7-8 cm over the kell, = the suzukies gives more drag and lower speed

When you say 15cm where are you measuring from?

searafting.no · 13 July 2006, 22:09

measuring the distance from cavitation plate down to the keel, normaly a boat that is built for a 25" engine is 25" from top of transom and down to the keel, with a Verado you could fit a 20" engine on a boat with 25" high transom

joakimhansson · 14 July 2006, 20:10

For me all engines looks the same under water. Why can you put a mercury higher than other brands.....

searafting.no · 14 July 2006, 20:48

first of all the prop on the verado is 10 cm further back than other engines, the reason for this is that the verado has different mounting bracket than other engines on the market.

when the prop is further back, the prop allso get "cleaner" water and it allso could be lifted higher, and the shape of the gearcase and of course what prop you run will effect the result of grip and top speed.

We are going to test a "high five" merc prop on the 250 verado, but our boat will be rigged for top speed with 12 peoples on board so we will test a 19 and 21 pitch prop. hopfully we will see speeds of 45 knots or more with 12 peoples onboard.

BVR · 15 July 2006, 17:10

The standard formula to use is Square root of (Weight in tons x HP ) x Constant = Speed in Knots. The constant for a planning hull is probably between 2.5 to 3
So if you know the all up weight (include absolutely everything ) of you rib and given that you will know your existing top speed and hp you can determine the constant for your boat. So then you change the hp to give the speed you want. Easy with a spreadsheet. All a bit theoretical I know but will give you a decent result to start from and you can play with the HP to get any ( within reason) speed you want.

www.reesmarine.com