When talking about the impact of surface roughness on hull resistance, there is only two reliable ways to study it. Either real life side by side testing of identical sister ships in way of speed trials or, if they operate on the same route, a long term monitoring of fuel consumption. It cannot be done in model scale, as the scaling is done according to gravitational forces and not based on frictional/viscose forces. Reference tests could be done for a fully submerged object (e.g. submarine, or propeller) in cavitation tunnel, where the viscose forces are closer to right scale. None of the cavitation tunnels are capable of getting the viscose forces exactly right, as it would require almost vacuum and very high velocity.Alternatively the fluid (in model scale) would have to be something else than water.
However full scale RANSE (computational fluid dynamics) simulations are very reliable when it comes to analyzing resistance. Based on model scale benchmark testing, the accuracy is well within 1%. Hull resistance can be divided in two major components; Friction resistance, which is dependable on the surface area, velocity and surface roughness. The second major resistance component is pressure resistance, which is depending on the volume, the shape of the volume and velocity. Pressure resistance (pressure variation on hull surface) is creating the surface wave. If the velocity is very small or the shape of the volume is close to ideal, the surface wave almost disappears. At very high speeds surface wave is inevitable.
Physically there is only two practical ways to reduce friction resistance; Either lowering the velocity or lowering the surface roughness. Surface area cannot altered much, as for load capacity reasons, ship needs certain size. The bigger and slower the ship is, the greater role the friction resistance plays
With traditional antifouling the typical surface roughness of new coating is about 150 microns (150 thousandth of a millimeter). This is based on numerous measurements done for fresh coatings.
Based on real life experiments as well as backed up by cfd simulations, for medium size (close to 200-m) and medium (~15 kts) speed range ships, every 10 microns change in surface roughness seem to have about 0.5% impact on overall (calm water) resistance. I.e. 100 micron hull is about 2.5% better than 150 micron hull.
For best antifouling coatings, we have seen surface roughness measured to 120 microns. That seems to be the limit for those products.
Soft foul release coatings we have seen to measure in range of 50 thru 70 microns. We have never witnessed soft foul release coating to measure below 50 microns. Soft foul release coatings are rather expensive They also damage easily. Thus, soft coating is not feasible solution for large ship with several annual harbor calls.
Hard foul release coatings seem to range from very poor surface smoothness to very good. Seaspeed is the only product we’ve seen capable of below 10 micron roughness texture. We have also seen some long term operational data, that is supporting the surface measurement data. Conservative analysis show minimum 5…6% gain in fuel consumption compared to similar sister ships with traditional coating.The 5…6% gain is relative to surface roughness measurement only. The incremental fuel savings resulting from the Seaspeed coating hydrophobicity is most certainly a significant factor and appears in operational data, but exact determination by cfd analysis is not yet possible.
We have also some experience with technologies such as air lubrication (air bubbling), but the outcome is inconclusive. In some cases the used energy is in or above par with the energy saved in resistance. In every case the resistance is less with air lubrication, but ships with deep draft often require too much energy to pump air deep underwater to make the concept economically feasible. For many owners,
even 5 year pay back time is too long.
A Naval Architect
ln Novembe r 2016 we dry docked HSC Francisco to carry out scheduled maintenance and
programmed repairs. This was the first dry dock of the vessel after the starboard bow damage
repairs we carried out in March20L4 shortly after the vessel started operations in the River
During the 3 years of operation we did not notice any impact or decay in the ship’s performance. Both vessel speed vs turbine power and fuel consumption remained consistent from day one.
With the vessel in dry dock we could confirm that the underwater hull was in very good condition and did not need any repaint. The surface of the paint was smooth and the coat thickness was satisfactory.
The performance of the underwater hull paint has been remarkable; since HSC Francisco started commercial service in the River Plate , sailing the L10 nm route between Buenos Aires and Montevideo twice a day, the vessel has accumulated a sailed dlstance of over 360.000 nm
at a service speed of 50 kn .
This is certainly a very good result for SeaCoat Speed-V and we expect that we will only have to do a iepaint in our next scheduled dry dock 2 years from now.ln the mean time, I will keep you informed of any occurrence or finding. Thank you for your suppor
BUQUEBUS’s technical office
I am writing to you as a seasoned Marine technical professional having 45 plus years of technical experience and design responsibility in the maritime industry around the world.
I met John Bowlin in 2009 while Senior Technical Project Manager for INCAT, a world renown designer and builder of wave piercing Catamarans. We assessed the novel hull coating technology offered by Seacoat at the time, having completed approximately 6 months of live in water testing, and specified it on Incat vessels with exceptional success over the last ten years.
Although retired from main stream at this writing I have reviewed the newest technology offered by Seacoat and feel it is highly advanced from both technical & functional viewpoint and exceeds the environmental regulations globally for all types of vessels.
In summary I feel the Seacoat V 10 X ULTRA has a phenomenal future in the maritime Industry. If you require any additional information please contact me via email to email@example.com
Technical Marine Consultant
Sorry I have not been in touch earlier but in order to give this product a fair trial and give you a review it was not something I could do within weeks of applying the products. It has now been approximately four months since we re-launched the boat with the Sea-Speed V 10 X ULTRA clearcoat on initially the boat outperformed all data that I had recorded. It was more economical up to 13.5 litres an hour at cruising speed had 8 knots more top end and generally felt more nimble in the water. Having left the boat for six weeks without using it we found there was Very slight growth we then used the boat for the day to go fishing as we had the green light that we could fish from the government and on our return we found all the Growth had disappeared the only growth remaining was on the rear end which I lightly brushed and came back to New. So far I am extremely pleased with the product and hope to keep you up to date with my findings especially when it’s lifted out for engine maintenance and jetted off.
When applying the clear coat I went up the avenue of starting from scratch so we basically stripped the old anti foul off till we were back to gell coat. We then used the clear coat epoxy prima. Gave it 2 coats sanded lightly in between coats and got an amazing smooth finish. When looking back applying the prima was the hard bit. The clear coat was then applied about 5 days after the prima as conditions were not the best in terms of outside temperatures and dampness. The clear coat is a dream to work with it covers really well and quick. The finish was ultra smooth and was well worth all my effort in stripping the old paint even though it is not necessary.
Thank you for all your help and supplying the product will be in touch soon as my brother would like to place an order. Will keep in touch with some more feedback.
Sports fishing boat owner