Improving ship speed

Hi,
I have a twin screw passenger ship with specs as bellow :
L : 22.8 m
B : 6.5 m
D : 0.8 m
Disp : 44.7 MT in full load
Engines : 2*610 kw @1800 rpm
Propellers Diameter : 30 inch
Propellers Pitch : 37 inch
No. of blades : 5

with these specs, ship's speed is 15 knot that its so few with these engines.
how can I increase my ship's speed?
I just calculated a new propeller with B-Wageningen series for increasing propellers diameter, but not sure of its operation after producing and assembling that will cost a lot.
What should I do for improving its speed except this way? what appendage should I add to hull for improving the speed?
Is there any reference in this case?
Some pics of the ship is attached
Awaiting anyone's respond.

 

Probably a bulbous bow will improve speed somewhat. A bulb, low volume, helps lifting the stem (changing the trim) and produces greater waterline length.

 

You are right, the speed seems low, considering the available power, the displcement and length. What is the gear ratio (or is it 1:1?)?

 

I hope not. At that speed propellers seem a fan.

 

I did a quick check and with that power, displacement, etc. the best I can get is 15.5 knots.
Sure your got the prop right???? 37" dia x 30" pitch makes more sense but I don't know the gear reduction.
Bulb bow might help but the shallow installation could throw up some spray. Get some good windshield wipers

 

Is this a one-of-its-kind boat ? If not, it would be interesting to compare with sister vessels, as to weight, power, speed differences. The presence of those strakes running all the way along the bottom seems like an anomaly, they are doing nothing useful, I would say. Looking at the considerable vee at the stern, it is to be expected it would squat quite a bit at 15 knots, and those trim flaps would be somewhat ineffective in countering that, at that modest speed. Maybe drop 10 tons and it is a different story.

 

this is a planing hull, I think a bulbous bow will be out of the water over 10 knots.

 

whitepointer23, sure you have very strong reasons to believe that but I do not see how a ship of 44 tons, 22.8 m in length, 15 knots, can reach the status of "planning".
Of course, if you're right, what I said is nonsense.

 

I can't see how draft is just 0.8 metres, unless the propellors don't count !

 

Taking as a reference the diameter of the propeller could deduce that the draft in the transom is 1.2 to 1.3 m. (area in red, without propellers)

 

What is 610 kw in hp terms ? The boat probably needs more horses.

 

I was looking more at the hull design in the pics, but you are right , 44 tons is a lot to get on the plane.

 

610 kw = 818 hp

 

With so big engine power, you should ideally be able to push that ship to around 25 kts. This number is based on the attached resistance curves, which can give you an approximate ballpark figure for a first estimate. The underlying assumptions are that the CoG of the boat is in the correct position and that L=22.8 m in your OP stands for LWL.

At 15 kts, your ship should require approx. 400 kW with 65%-efficient props. So either your propellers are working at less than 30% efficiency (cavitation, barnacles or whatever), or your engines are badly underperforming, or the trim of the hull is so wrong that it creates too much drag, or the combination of these factors.

 

Must be plenty of bow lift to be fitting those trim flaps, isn't that amount of vee, aft, unusual in such a boat ?