10% faster for $100

FishStretcher · #1 01-02-2013, 03:53 PM

Now that I am a little less of a Seacraft newbie, I thought I'd repost some wisdom that was handed down to me by the guys on the board who really know boats.

When I got my boat- a 20 foot master angler- I immediately repowered it with a Yamaha F100. It is lighter than the 2 stroke Yamaha 175 that was on it, but only by about 40 lbs. And the F100 is known for being a low torque high revving, but efficient motor. With the help of Fr. Frank, I purchased a hydroshield- a delta wing that flies under the skeg. It helps you play safely in shallow water and helps with low speed planing. But at the cost of more drag and a bit of top speed. With it, I can plane at about 13 knots singlehanded with the 60 lb kicker and the F100 on the transom.

With a 12-3/4 x 17" four blade aluminum prop, that is. The prop is supposed to help you plane by providing lift, too. But with that prop I was pulling 26 knots (30MPH) at 5600 RPM, and a bit less with a full crew.

I didn't like the performance out of the hole and wanted to spin the motor a bit faster, so I started experimenting. I moved the motor up a notch. Now it has the *anti ventilation plate* (forgot to add this earlier) between 1 and 1-1/2" above the keel. It was previously just above the keel. That was worth probably 150 RPM and almost 2 knots, and was free, less a tube of 3M 5200 adhesive. (I have a hoist, and do my own work). The motor couldn't go higher though, as it would blow out in turns if I didn't trim properly.

Then I changed to a 13 x 15" 4 blade aluminum prop. That allowed me to pull to redline (6000 RPM), and the boat *jumps* on plane now. Plus it picked up about another knot in speed.

I am sort of a discount boater and I fish up against the shore, so I have never had a stainless prop. I suspect with more prop tweaking, there is more to be had, or by changing to a top water anti ventilation plate wing, there might be 2 more knots in it, but I haven't had the money or time to try yet.

gofastsandman · #2 01-02-2013, 07:51 PM

Nice work Grasshoppah. Get the Hoppah. Get the Hoppah.

eggsuckindog · #3 01-03-2013, 07:57 PM

the anti cavatation plate is not supposed be in the water, its designed to be above the hull bottom at least an inch

since you used 5200 any further motor adjustments will be hard fought endeavors - not sure why you chose that but its there now.

Does Seatow and BoatUS not have services in that area?

FishStretcher · #4 01-05-2013, 10:06 AM

Quote:

Originally Posted by eggsuckindog

the anti cavatation plate is not supposed be in the water, its designed to be above the hull bottom at least an inch

since you used 5200 any further motor adjustments will be hard fought endeavors - not sure why you chose that but its there now.

Does Seatow and BoatUS not have services in that area?

I have zero problems removing 5200, and did this once before with this motor. But I have an air wrench and a chainfall and an engine hoist at my disposal. So I didn't notice.

Unlike the other devices, this wing is always wetted, and skeg mounted. Like an america's cup "wing keel". Fr. Frank had one, and turned me on to it. I might try a conventional anti ventialtion plate mounted device someday to compare.

We do have towing services here. But I fish places where you would lose your boat if the engine didn't restart or you couldn't get a kicker going in less than about a minute. Like the mouth of the Piscataqua and Merrimac. The Piscataqua is really treacherous with an 11 foot tide, a 4 knot river current on top of tidal movement and it is an all granite bottom, so you go from 80 feet of water to an outcropping in a very short drift. Plus, most months of the year, the water is VERY cold in the Gulf of Maine.

At least that's how I see it. And it is so rough with all the water running that I can almost never get the F100 to full throttle there, so a soft landing off the waves caused by the intersection of tide and river current at the river mouth is a huge plus over speed I can't use.

eggsuckindog · #5 01-05-2013, 12:03 PM

11ft is serious tide, I see your point, no waiting around cracking a beer waiting on seatow

I was thinking is was plate monted, glad its working

Fr. Frank · #6 01-08-2013, 09:23 AM

Quote:

Originally Posted by FishStretcher

I have zero problems removing 5200,

If you can remove 5200 that's bonded to the gelcoat without removing the gelcoat as well, then....YOU THE MAN!!!

erebus · #7 01-08-2013, 06:23 PM

Quote:

Originally Posted by Fr. Frank

If you can remove 5200 that's bonded to the gelcoat without removing the gelcoat as well, then....YOU THE MAN!!!

Heat gun and a piece of plexiglass with the edge sharpened on a belt sander into a scraper.
Plexiglass wont scratch the gelcoat, but it will cut and scrape off the warm 5200.