My boat going slower and slower.

Ok, I've never had it done, but I can safely say that whatever improvement it might bring, it can only translate in higher speed AND higher revs. Wen you say that you lost just speed at the same revs, in practice you're ruling out a/f (or anything else drag-related, for that matter) as a possible reason.
 
And I can safely say, that if I ask the boat to do 3500 revs, it does do, same as if I ask it to do 1500 revs to toodle up the river. /forums/images/graemlins/grin.gif

It's just not going as fast at 3500 revs, as it used to. /forums/images/graemlins/frown.gif

It's just been antifouled and the props examined (Not personally).
 
Thats the most sencible answer I've had, I'll empty them now.................................................................................................................................................................................................................................................................................................Yep, ten knots added emmediatly. Thanks for that. /forums/images/graemlins/grin.gif
 
I think everyone has missed the obvious. Surely the consumption of too many Fray Bentos pies is the cause? Both my boat and I have slowed down over the years. Mostly caused by the increase in weight of yours truly /forums/images/graemlins/shocked.gif /forums/images/graemlins/tongue.gif
 
We've already discussed the effect of old antifouling already HERE and I think the concensus was that, due to evaporation on drying and the stuff falling off over the years, it's unlikely that a boat would get appreciably slower due to the extra weight of antifoul paint applied over the years
I'm with some of the others. I think it's more likely that it's a prop issue. I had a similar thing last year. My engines would never rev to their max (I know yours will but hear me out) even when the boat was light and hull clean. The props looked A1 but, since the boat came with a spare set of props, I swapped them over anyway and hey presto, another 50rpm and 1.5kts. I couldn't see any difference between the props at all but the spare set worked better than the ones that had been on the boat for years. The other issue might be the engines. Are you happy that they are still giving the same power output as when new? Engine power does degrade over time and usage
 
H

I reckon its all things together, manky rough antifoul, full ashtrays, manky old props, that extra 40 gallon of diesel you cart about, the junk on board.

Remove all the junk and run the fuel right down and see how it is.
 
Think your probably right, just a little bit of every thing. Plus maybe every where I go, the tides going the other. /forums/images/graemlins/frown.gif

But I've still not got an answer from some one who did take it off, neither do I know why the antifouling had been striped off ten years or so ago, when I bought the boat. There must have been a reason??

The inflight refueler is empty at the moment, by the way, and I cant think theres any more weight on board than there ever was.

Engine power?? Well if it's going round at 3500 revs same as before, then the props must be wizzing round at the same speed, or pehaps my clutch is slipping. /forums/images/graemlins/confused.gif
 
Was it stripped off so that your surveyor could see anything untoward? Anyway you should not be charging around at those obscene speeds leave that to the young uns, they will eventually slow down to our speed. or shake themselves to bits in the process.
 
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Have you tried emptying the ashtrays? /forums/images/graemlins/grin.gif

[/ QUOTE ]

And let Kawasaki out of the locker /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

Andy
 
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But I've still not got an answer from some one who did take it off, neither do I know why the antifouling had been striped off ten years or so ago, when I bought the boat. There must have been a reason??


[/ QUOTE ]

You checked the tacho's are reading right?

I doubt its rough bottom, a dirty bottom maybe, but not rough, when TCM did his copper foil shenanagins it was all wrinkled and peeling off when we brought it to the Solent and it dint slow us down, then when he did the copper powder mixed in with the antifoul the bottom was as rough as a badgers arse and it dint slow it down.

Junk on board, boat gaining weight due to water ingress, slightly manky bottom, windage, tide, trim tabs angle of dangle, manky props, residue from the Lancashire treacle mine, full to the point of exploding holding tank, all those....
 
1/ Ive never seen two taco's read the same. The boat always goes faster from upstairs than down

2/ Ive always found the state of the bottom, is far more important than any weight issues. The odd half a ton, hardly makes a difference.
 
After re-engining my 26' cruiser she got close to 30 kts but I thought the a/f was pretty rough after several years even after it was painted.. scraped it back this year and re-painted.. gained about 3 knots and planes much easier and at lower revs..didn't even manage a great job of the scraping with the hand scraper but it helped. Also boats do get heavier with age as the hull takes up some water which can have some effect... I would definately give the antifoul a try... Iain
 
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1/ Ive never seen two taco's read the same. The boat always goes faster from upstairs than down



[/ QUOTE ]

Love it! I once made a sailing yacht go twice as fast by fitting a GPS for a friend - the log read three knots off when sailing at 6 knots!
 
Really, are you sure some (most) of that 3 knots wasn't the hull and props being cleaned when it was lifted? Boats should theoretically go slightly faster with a less flat surface, so long as it's smooth, as it breaks the tension between hull and water and reduces friction (same reason they put dimples on golf balls, and why boats go faster in slight chop than flat water).

Anyway, HLB kept asking the same question till he got the answer he wanted, so I think he'll be giving it a go /forums/images/graemlins/grin.gif
 
As it happens, theres a 52ft boat here being blasted. There doing it to save fuel and improve speed. First guy I spoke to, said he did not believe it, till it was proved to him, but boats wentt much quicker. Then I spoke to the blaster man, he said he'd just done the fisheries protection boat and they've saved a load on fuel.

Cost for the 52fter £400.

I've never seen a racing boat bottom, that looked like a golf ball. /forums/images/graemlins/grin.gif
 
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I've never seen a racing boat bottom, that looked like a golf ball. /forums/images/graemlins/grin.gif

[/ QUOTE ]

No, but you may have seen one with a stepped hull, or air injection? Anyway, theory and practice often don't match, so it may well work. If you get it done it will be interesting to see what effect it has.
 
Nick_H it wasn't the cleanliness of the bottom cos it was spotless when it went back in on sea trials with the new lumps... but your golfball theory might have some relevance because, as I said, my scraping was not great so maybe I just got it to optimum golfball'ness!! cheers Iain
 
The tides around Anglesey & N Wales are strong +/- 3-5kts springs are common. You really do need to try runs in opposite directions to even this out. GPS can only give SOG not speed thro' water.

As I have just saved you £300 odd squid, that's another large Scotch you owe me! /forums/images/graemlins/laugh.gif
 
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