WAIP is Basis of WAIP Ferry Misaki WAIP devvelopment WAIP Inventor Takahashi,Yoshiaki WAIP install record WAIP_Agent WAIP_Report WAIP contact_us
For displacement type ships to advance in sea/pure water,there are two(2) kinds of resistance to overcome : Wave making resitance and Frictional resistance( Drag from now on).

Regarding Wave making resistance, many engineers, scholars and governments made efforts to reduce and resulted in attaching Bulbous Bow to almost all ships.
Almost 30% reduction of total power was observed by attaching Bulbous Bow compared with conventional no Bublbous Bow ships.
And now, it looks no more room left for reduction from practical and technological design viewpoint.

As for Drag , many people tried and studied worldwide to reduce for example selfpolishing paint invention, microbubble generation and air film making at the bottom.In one of those trials,compressors for microbubble generation were got on board and run for tests in September,2001 in Japan. The results showed in some cases explicit Drag Reduction was obeserved.Even in this case,power for driving compressors was huge and ran out almost gain of Drag Reduction by microbubble.

The inventor of WAIP,Yoshiaki Takahashi, conceived the WAIP concept as early as in 1998 to lessen required power to generate microbubble.
But WAIP showed in practical application and in laboratory tests,generation of Ultra Fine Microbubble as well as very small aditional power required for generation of Kelvin-Helmholtz Instability.

WAIP can reduce total power by 15% and/or more by Drag Reduction alone.

TEST No -1 Pre-Test Prism type

DATE In August,.1999
Test name of objective ・Sea Trial by "Kiku Maru"
・Triangular plillars like prism:40mm sides were allocated athwarthip one by one at the bottom to generate MB(microbubble) by the negative pressure at the rear of the prism. Total pillar length is 1.75m. This is called Prism Air Induction Pipe(WAIP)
Result ・Generated nagative pressure can induce atmosphere and make MB.
・It is comfirmed that MB wil not increase Drag.
・Results were presented at ONR Workshop at Newport, Rhode Island,USA, Gas Based Surface Ship Drag Reduction.
R&D Thema ・NO comparison of with and without WAIP.
Efectiveness of WAIP shall be comfirmed next time
Remarks ・At town"Sai" Shimokita Peninsular conducted by three(3) volunteers including RDE
・Massive and Less expensive MB generation looked for.
TEST No 0 Pre test ( Ogival foil Type)

DATE In Marchi,2000
Test name of objective Sea Trial by "Yayoi Maru"
Result ・Removable Air Outlet configuration (3 type) were tested and confirmed their effectiveness.
・WAIP with Ogival foil tested.
・Measured by DGPS,Drag Reduction by MB was confirmed by this Sea Trial.
R&D Thema ・Necessity of foil improvement was confirmed.
Remarks ・Sea Trial conducted at Aioi bay .
・Serial tests deemed nescessary for foil improvement.
WAIP concept was born.

Circulating Water Channel at FEL

Put on a floor reversele, 3types of Air Outlet configurations. Extreme left is Ogival foil WAIP,middle is WAIP tested by "Kiku Maru" and extreme right is a cylinder,lawest hemisphere cut for MB generation by negative pressure at the rear side or cylinder

DATE In september,2001
Test name of objective

・At Fluid Engineering Laborarory(FEL) 3 types of Air Outlet configuration were tested from Drag Reduction performance.






・WAIP was selected from 3 types of Air Outlet configuration.

Ogival foil WAIP
Aspect ratio or Ogival foil is only two(2)


R&D Thema

・Foil improvement to Aero foil was considered essential.


・Funded by DSO National Labporatories Singapore

Beginning of FEL serial tests for Air Outlet configuration




In January,2002

Test name of objective

・3 kind of aerofoil were tested ΔDo and 、ΔR with WAIP configuration ( foil height,attack angle etc.) were measured.

ΔDo:Drag increase by WAIP itself
ΔR:Drag reduction by MB generated by WAIP


・Measurement system was established forΔDo and ΔR.
・Drag reduction curve was approximated by rational function.

R&D Thema ・WAIP configuratioin parametes' were considered essential for fixing.  

・Funded by RDE, Rational function approximation for Drag Reduction.


3 kind of Aerofoil:

In May,2002

Test name of objective FEL serial tests were conducted
Result .・WAIP configuration parameters fixed;foil length,width,foil connection with support etc.
Here Aspect ratio:4 contst.
Method for apprecating ΔDo and ΔR together was invented.
Definition of Compensation Distance (C/D) was born.
R&D Thema ・Actual See Trial was deemed essential for fixing suitable Aspect Ratio and attack angle.

・These tests were conducted under collabofation with RDE and DSO National Labolatories.

Definition of Compensation Distance (C/D) was born.


Each one WAIP for both sides.WAIP with Aspect Ratio:4 was used.Attack angle:16 degrees.

Click and see MB through acrylic windows at bottom .


DATE In July,2002
Test name of objective See Trial by "Adventure2" at Imari bay

・Net gain (Drag Reduction - Drag increase ) was observed positive.
・MB by WAIP was observed through acrylic windows at the bottom. MB did not diverge nor mix togather

.・Then comes the idea to allocate \WAIPs athwartship for increasing Drag Reduction.

R&D Thema

・Tests for multi WAIP was considered esential.


These tests were conducted under collaboration with RDE and DSO National Laboratories

Two(2) WAIP First Sea Trial


TEST No 5 WAIP 2nd Sea Trial  
DATE In December,2002
Test name of objective ・Adventure2 was used. WAIP with Aspect Ratio:6 provided. Attack angle:12 degrees
Result ・Two(2) WAIP Net Gain:4% observed
R&D Thema ・Sea Trial with multi WAIP was considered indispensable.
Remarks ・Funded by Governmental Organization and RDE
Explicit Net Gain observed
TEST No 6 Drag Reduction tests by WAIP  
DATE In June,2004  
Test name of objective ・Attack angle serial test at FEL for slower ship  
Result ・Attack angle 12.8 and 4 degrees test  
R&D Thema

・12 degrees was selected


Remarks ・Funded by RDE  
TEST No 7 Drag Reduction tests by WAIP  
DATE In July,2004  
Test name of objective ・WAIP with air compressor feasibility was tested at FEL  
Result ・Smooth MB generation when air/water boundary lowered by compressed air was observed.  
R&D Thema ・Sea trial by WAIP with air compressor ship wad deemed essential.  
Remarks ・Funded by RDE
・WAIP with air compressor observed feasible.
TEST No 8 WAIP 3rd Sea Trial Philippines
Suntander Ferry 1

Lpp*Bmd*Dmd=28.8*5.45*1.55m, 700ps
DATE In October,2004
Test name of objective ・16 WAIPs equipped 30m ships, Santander Ferry 1 Sea Trial was carried

・At strait between Cebu island and Mactan island, speed test wad carried out with 16 WAIP. Max 14.3% total power saving was recorded.
・Two(2) WAIPs in line with longitudial derection effect ( called Tandem effect) was observed independently effective.
・Two(2) WAIPs side by side was also independently effective.


R&D Thema ・Direct fuel saving observation was considered essential.
Remarks ・Funded by MLIT
・16WAIP Sea Trial
TEST No 9 WAIP 4th Sea Trial Philippines  
DATE In February ,2005  
Test name of objective ・Santander Ferry 1 operated in route was used
・The rear most 6 WAIPs were removed, because no positeve effect exerted. 10 WAIPs were effective.
・Fuel flow meter was set at fuel injector and outlet of two(2) engines and measured with air and without air.
・Without air could be realized with clogging in the air intake on the deck.
Result ・Just less than 15% fuel saving was observed  
R&D Thema ・WAIP with air compressor equipped ship sea trial is the last remained for actual application of WAIP to all kind of ship.  
Remarks ・Funded by MLIT Actual measurement of fuel saving observed.  
TEST No 10 WAIP 5th Sea Trial in Tachibana Bay,Nagasaki Japan

DATE In August,2005
Test name of objective ・New Ferry MIakaki was used

Shipbuilding Research Center of Japan carried out this Sea trial on 31st August,2005.


R&D Thema ・By this WAIP with air compressor equipped ship Sea Trial, WAIP invention will be finishied.
Remarks ・Funded by MLIT
14 WAIP with air compressor Sea Trial
Words Explanation:
Aspect Ratio For rectangular wing, wing width over twice powered wing chord length is Aspect Ratio.
The larger the Aspect Ratio, the smaller induced resistance.
Attack Angle Angle of wing to in coming laminar flow
Prism Configuration of a rod section of which is triangular.At first,this Prism was used for negative pressure making on Kiku-maru.
Ogival One of the most simple wing. One part of a pipe section of which is arc 120degrees or less and which has the same thickness.
aerofoil Most advanced and refined wing configuration.
One of the most famous aerofoil wing is NACA wing series.
Chambered WAIP Now called WAIP with air compressor. WAIP assited by compressor.
Lpp*Bmd*Dmd Principal particulars of ship
ΔDo Additional resistance by protruded wing of WAIP
ΔR Drag Reduction of the measured part of test facility at FEL,0.5m wide and 2.6m long plate.
Compensation Distance(C/D) Length of 0.5m wide measured plate in which delta R ia equal to delta Do.
The samller C/D,the better configuration the WAIP will have.
WAIP is Basis of WAIP Ferry Misaki WAIP devvelopment WAIP Inventor Takahashi,Yoshiaki WAIP install record WAIP_Agent WAIP_Report WAIP contact_us
WAIP saves our Earth and your money