140 suzuki on 20 MA
 

I am running a 140 zuke on a 20 Master Angler and though I love the economy and reliability my top end is only 32 knots. This is plenty fast for my needs as you can seldom open up a 20 footer offshore anyway, but I do wonder if something is wrong with the set up. Prop is a 14x19 aluminum. Anti cav plate is about 2" above straight edge on keel. I get my max spped by trimming up a bit with tabs up. This with one person on board, 60 gallons fuel, two batteries in front of console and a large fiberglass t-top. Boat is a little squirrely at this speed so I don't care to go faster, it just seems like it should from talking to other people. This at 5800 rpm or so. Thanks for any feedback.

Re: 140 suzuki on 20 MA
 

I'm no aerodynamics expert, but consider your large t-top is likely affecting your speed in both drag(acting like a parachute) and exacerbating bow-lift(more like a lifting foil) simultaneously pushing your stern down. That would account for the front end getting squirrely at speed. Likewise trimming up (bow up) would theoretically increase the drag on the top.

What prop model are you using? I would guess with the extra weight of the 4-stroke, albeit a light one, you want a wheel that lifts the stern a bit. Mounting height-wise, 2" might be a little high but with a big wheel it might not hurt too much.

If you can easily remove the top itself you might try that and give it another whirl. I'm guessing you'll easily pick up 3-5 mph.

Re: 140 suzuki on 20 MA
 

I whouldn't consider lowering the motor as it sits so low now I worry about it being underwater so much. The bracket on the engine is currently about 1" or a bit more above the transom. I will definately raise transom to 25" when-if I repower.

Re: 140 suzuki on 20 MA
 

I hear that, harry.
Didn't realize you had the 20" shaft. I have similar concerns with a 20" on a Seafari.

I would think 140hp making 5800rpm with a 14x19 should push an MA a little better than that. Can't help but think that there's a more effective prop out there for you. Anyway, try to identify your prop model - perhaps its geometry is not optimal for your MA.

If it's not too much work, try removing the hardtop, and seeing if its drag is not the culprit. If its only a handful of bolts it's not much time lost on a simple experiment.

Good luck. keep us posted, Iv'e been looking at Zukes lately based on some of the other guys experiences. :cool:

Re: 140 suzuki on 20 MA
 

The top is going to have to come off soon anyway as the deck is getting pretty bad and I have to do something about it. You can feel the floor moving on port side when running in a sea. I think the console is the main thing holding the top on on that side. That is a good idea to run it without the top. I was thinking of changing to a small dog house as on my previous 20 SF and this might help make up my mind. The weather in MA is getting pretty dicey and this may have to wait till spring.

Re: 140 suzuki on 20 MA
 

I removed the T-top today and ran the boat on a lake. Very calm. My GPS antenna is on the T-top so I had to use a hand held. Just hit 37mph, about 32 knots. I am kind of suprised that there is no real improvement in speed, although the boat did feel more stable. That T-top is a heavy sucker.

Re: 140 suzuki on 20 MA
 

Sorry to suggest the effort. I really thought you would gain something. :eek:

Re: 140 suzuki on 20 MA
 

You might try running the equivalent stainless prop if you're already in the right rpm range for that motor with the load you normally carry. They typically have a little more cup, pitch or diameter to compensate for the thinner blades and keep same load on motor. Could be worth another 2-3 mph at most.

Re: 140 suzuki on 20 MA
 

The top had to come off anyway because of the deck. Considering how much it moved around it sure was a bear to break free of the deck. I had to use two log splitting wedges and a sledge hammer. I'm not looking forward to seeing what's under there!

Re: 140 suzuki on 20 MA
 

I think I remember Trayder mentioning his boat topped out around 32/34 knots with the 140 Suzuki.

Re: 140 suzuki on 20 MA
 

I would pick up a 3 blade 14x20 stainless prop. that aluminum prop is probably flexing due to the boats weight. I get 42mph out of my boat. also if your boats decks are soft you might have alot more weight in the boat than you know about,I.E. water logged decks. I just bought a 14x20 powertech. I am going run it soon I will let you know what the results are.

Re: 140 suzuki on 20 MA
 

I'm glad to see those numbers from Trayder's boat. Pretty much the same. If I wreck my prop I'll get a stainless one as I saw a performance increase on my previous Seacraft with one. That was a 20SF with a 120 Evinrude looper but I don't remember the prop sizes. I hope to open up the floor this week to see what I'm up against when the snow melt. Waterlogged wood and or foam could be an issue i suppose.

Re: 140 suzuki on 20 MA
 

Billy, I'd be very interested in the numbers on that new prop.

I bought Trayders boat; this summer on flat calm, one person and about 30 gal in the tank, My WOT was an indicated 40, GPS'd at 38 kts. Aluminum 3-blade prop (I believe 13x 17, but don't have it handy). I believe this boat is a bit lighter than most 20s.

Re: 140 suzuki on 20 MA
 

Loon what your RPMs top out at ? 13x17 is too small. I think its atleast a 14" prop. When I first ran my boat with a 14x16 I had way too many RPMs. I then went to a 14x18 that came with the motor still over on RPMs. now with a 14x20 I and still running at 6200 so I want to try a 14x22 when I find one ebay. I might be able to get another 1 or 2 mph out of her!

I dont like aluminum props as the tend to flex out at high RPMs

Re: 140 suzuki on 20 MA
 

I would like to know what your boat weighs, I want to drive mine across the scale to find out .

38knots is about 44mph. that is great speed.

I would bet it would be even faster with a 14x20 stainless 3 blade.

Re: 140 suzuki on 20 MA
 

Opened up about half of my deck today. Sure is a lot of water in the deck plywood. The wood, though soaked, doesn't seem rotten, just delaminated and not sticking very well to the glass. The foam between stringers is soaked to a depth of about a quarter inch on top but when I dug into it it's suprisingly dry. Don't know how much this water weighs but the whole mess has got to go.

Re: 140 suzuki on 20 MA
 

Got into the back corner of the barn today: my prop is a 3 blade aluminum 14X20