Slime line on hull and boatspeed

[backman]

1st spring w. a DE after 15 years with a deep V. I've been in the water 2+ months and noticed a small loss in speed ( 1/2 knot or 2.5%) and a small increase in fuel burn(4-5%). I took a look along the waterline under the stern and see and feel a slime covering that goes down as far as the turn in the bilge. It rubs off to my hand.

Is this where my small speed loss and fuel burn increase is coming from? In a deep V it never mattered because once the boat was on plane the waterline was a foot proud of the water.

 

[Duke]

Weight?

If the rest of the bottom is still clean, I doubt if the slime line would take .5 knots off your speed. Have you been adding weight to the boat since it went in the water? Fishing gear, food, drink, etc. It is amazing how the weight of small items adds up.

 

[backman]

Probably 500# of stuff added; 500 out of 20,000 is 2.5%....hmmm

 

[steveinak]

If you have access to a haul out grid put the boat on it and spray the hull with clorox bleach, it will kill off the slime and when you float again the slime will just wash off. Might be the slight loss you have but i'm thinking its the extra weight. Boats is like women the older they get the heavier they get !!

 

[jerseysportfisher]

Boats is like women the older they get the heavier they get !!

Not mine steve, ever since that new fangled contraption called the sawzall came out, its like lipo!!!

 

[nickyp]

perhaps growth on the running gear, specifically prop. although 2 months isn't that long.

 

[greg]

Could it be a different blend of fuel? We've switched from winter blends to summer on gas, so maybe they tinker with diesel also. You can try a cetane boost to see if it has an effect.

 

[backman]

After a pair of 1 hour out/1 hour back trips this weekend I'm back to normal. I did use a deck brush from a skiff and scrub the slime off along the waterline and down to the turn of the bilge. It did extend as far as my brush could reach.

The keel and rudder "looks" clean; ie I see blue not brown. but I'm not going swimming till the water hits 65!

DE technical question - where on the hull does a DE run on plane and is there any "lift" to stop the squatting at the strn?

 

[Duke]

Make?

What kind of boat is it?

 

[backman]

Northern Bay 36.

 

[backman]

Problem solved

Put in the wetsuit and flippers-and took a swim in Woods Hole today. I had slime from the waterline down past the turn of the bilge and perhaps 1' under the bottom of the hull.


Scrubbed it off and picked my 1/2 knot back up!

Lesson learned!

 

[BOSBoatMan]

NB 36? I don't suppose its one of the Hunter Scott builds, no?

 

[backman]

No - Maine built and finished - General Marine Hull, AJ Enterprise finished.