Hydrophilic bottom coat = extra speed?

[Starscream]

You guys crack me up. See what happens when boats go into storage?

I guess no one's tried the stuff so I'll give it a shot in the spring. I have my doubts that it can work on a Mac, but I am more or less convinced on the science of hydrphilic coatings. If you do a google-search for hydrophilic/ hydrophobic you will find plenty of science experiments and explanations on why it takes less force to drag a given form through water if its surface is hydrophilic.

Obviously, a 50 HP motor forcing a Mac through the water has a whole lot more going on than a water-tank experiment. It seems too good to be true, so it must be true. Anyone got some swampland in Florida for sale?

[waternwaves]

Don't get me wrong.
I am all for testing.
I own a few boats......of many different materials. I have tested many many coatings, waxes, polys, sealers, burnished epoxies etc. pipe wall coatings, seals, o-rings, control valves etc.

there is unlikely to be 17% difference in speed. (6kts up to 7 kts) due to that coating.

now, if you read my words........I did not say you could not find a 17% increase..... I say it is unlikely to happen due to a change in bottom coating alone.

prepping the surface, burnishing, sanding, fairing, evenly depositing paint coating etc...... each will have a part in the reduction in drag at displacment speeds. The addition of waxes (non polar materials) has significant effect on reducing form drag,

same as scraping the bottom of the boat moored in the water has an improvement in speed.
I am not a total idiot. I have done work and recieved payment for measuring drag forces in flowing plasma, supercooled fluids, and seawater at many temps and speeds,
drag forces are measureable. Comparing 2 absolutely clean hulls, one with a magic coating and one without is not going to result in that magnatude of speed differnce. hydrophyllic coatings generally increase viscosity of a fluid at the contact surface area, energy is required to lift the water up beyond the surface (due to decreased surface tension) , splash and spray hang on the boat longer, increasing the displaced volume of the boat, dissolved gasses in the water also are effected at the boundary layer.

There is a lot going on there at the boundary layer. but dragging a surface through the water that hangs onto the water better needs a lot of study before claims of that magnitude can be substantiated.

There are many reasons that hydrophyllic coatings are still being examined. Hydrophobic coatings (including waxes) have a long history of improving boat speeds.

Advertising changes far more than physics.

[delevi]

Is there a wax that can be applied over bottom paint without degrading its anti-fouling properties? Anyone try these with a measurable performance gain? Got the need for speed

[Highlander]

Leon

The best & cheapest & most ecomonic way to get that much sot after speed your after is to fly more rag . if you have a jib & a genny then cutter rig you do not have to go to the extreme I did "double anchor roller" set-up just a simple cutter set - up , same if you have a jib or a genny plus a storm sail jib set - up an inner forestay cutter rig , if you already have these extra sails as spares then the extra cost for the necc hardware is not much more just the effort to do the work ! of coarse you will have to have the necc. sailing experience to handle the extra effort & work to get this extra speed or practise it out first in light winds & work it out as you gain the expertise "this is for those who have not done or gone where Leon has !!! " Safety First !!!

So finnish off the Mod your working on & if you subarmine then you should have had your big Butt hanging off the stern " no Pun intended"

If you listen to guy's who have bought the new muscle head mainsail they will tell you how much speed it adds to the boat , the only fall back is when the wind gets gusty they have to reef !!!!!!!! Why ? because that extra sail area is way up high causing too much heel !!! . Not so with a cutter rig as the extra sail area is down lower & closer to the deck as proven by the video's I've posted . So finnish off that Mod & remember you are not moving extra sail area up but can if so desired in light winds . but just increasing the slot between the main & head sail " man that make's things happen "

J

[delevi]

John,
I got all the rag I need. I assurue you that if you sailed your McCutter in my pond, you would be reefing and using that strorm jib, not flying multiple headsails.... yes even if you complete your wing-keel mod. As for the bowsprit mod, I decided to take a pass. Instead, I'm going to get a heavy duty whisker pole which I will use for a spinnaker pole to fly the A-sail on deep reaches.

Cheers,
L.

[mikelinmon]

Lost it on that last try to post! OK, speed is worth somthing to me. My usual twilight race is 6 miles and takes about 2 hrs more or less. Up wind for 1 mile is actually about 1.5 miles, downwind and reach in harbor for rest, total 6.5 mile race. About 3mph. Even figure at 6mph, rare for a twilight race, the extra speed would be nice. Just how nice? We win or lose usually by one min or less, somtimes by only seconds after two hrs. Having new costly sails will keep us aheead of the also rans but only by 2 min or less. I'm saying two sails costing more than $1,000 each is responsible for one min in a two hr race! Rounding off everything, a one percent speed increase on a sailboat our size cost $1,000. That is for the first one percent. Once you buy that, the next one percent of speed increase will be very expensive, hard to measure. I have about 20 or 30 speed producers on my little V23, rotating mast, taller rig, $2,000 bottom paint, runners, four $$ sails, etc. Think I've got a speed advantage of one min in a two hour race over a well prepared, well sailed boat (that is 1%). So this stuff gives you one knot! Worth everything. No need to even think it over. Or maybe it does not work. No one I know would turn this down, I'd pay $10,000 for it if no one else wants it, course, I'd need to try it free! There is a tail of one fellow who bought everything possible to put in his tank, on his car, attached to his motor and up his tailpipe to improve his mpg. He figured GM and Ford didn't know about all of that stuff and he'd get really good fuel milage. Turns out after driving home his gas tank was running over and spilling on the ground.
mike Inmon

[Currie]

Mike, you have the perfect venue to test and post the results!

~Bob