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I just recently purchased a used 2014 sea chaser (by carolina skiff) 18 ft bayboat with a 115 evinrude etec motor. I have taken it out a couple times and max speed is only about 32 mph on speedometer and confirmed with gps. This seems a bit slower than what i expected. The hulls dry weight is 1500 lbs and it has 30 gallon fuel tank. It has the nonadjustable nauticstar trim tabs and a new stainless prop. Both times I went out was with only me, the dog and one ice chest. Does this speed seem accurate or should I be getting better speeds then this?

thanks
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Have the prop looked at. If it's worn or 'flattened' out you can loose mph.
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   Dulacdat
Two questions: 1 Are the non adjustable trim tabs allowing the bow to rise when you trim out the engine? 2 You said new stainless prop, did it come with boat or did you change it, what is the pitch of the prop?
I have an older 88 Evinrude on a Bluewave 180 V Bay. Cruising speed 31 mph at a little over half throttle, open it up and boat lunges forward to a top speed is 38mph with a 13 3/4' x 17 pitch. I tried a 19 pitch prop and the boat jumped out of the water quicker and did ok to half throttle, but when opened up boat no longer lunged forward and speed change was very minimal.
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   bullcoon
Check what manufacturer RPM range is compared to what you are turning at WOT... If your below you need a smaller pitch . If above you can go with a larger pitch . If you within range you can play around with different designs of props if you have the funds...
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Your probably going to get about 200 rpm variance per inch of pitch. It all boils down to turning manufactures recommended rpm at wide open throttle. Usually 5000-5500 rpm wot. Too much pitch results in not enough rpm at wot which could damage motor. too little pitch and you're over reving the motor. You could experiment with different props 3 verses 4 blade etc. but the rpm thing is most important. good luck
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Prop came with the engine, it's the viper ss made for that motor, I will have to check the size. I am going to remove the trim tabs and get a baseline speed and rpm numbers. I don't believe the trim tabs should be affecting top end that much but will see.
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If the tabs are helping with performance, I would leave them on. Work the prop numbers first and see what changes. Some prop shops will let you try them before you purchase. jmo.....
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Ya I'll plan on leaving the tabs but they come off real easy and so I just want to get some baseline figures. The boat doesn't ever seem to lift out the water so I wonder if they are bogging me down.
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   JOHN C.
FIRST, as stated previously-find out, what is the max RPM for your particular motor. SECOND, leave the trim-tabs on BUT RAISE the setting to the highest position so as NOT TO AFFECT planing/r resistance of the hull. THIRD, REMOVE YOUR PROP, bring to a prop repair shop, explain your situation and go from there. EVERY BOAT IS DIFFERENT...suggestions are only suggestions/starting points! SOUNDS like you need LESS PITCH in your existing prop...listen to the advice of the prop repair person for the best advice! John Castelluccio, Jr.
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John is spot on with his assessment. So was the other poster that asked if the bow raises when you trim out. If it doesn't the tabs are set too low causing too much drag. Plus the engine may be set too low as well. See if the cavitation plate of the lower unit is even or a little higher than the bottom of the boat when it's trimmed in all the way. If it's below the bottom the engine has been mounted improperly too low, and if thats the case all these other adjustments will not amount to a hill of beans until that has been corrected.
ARRIVE ALIVE!!!
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   bigjim
You should be able to get between 40 to 45 mph depending on how much that hull breaks free from water. Look up operating rpm probably 5500-5600 would be a good range for that motor light boat. Go run it with tabs up and see what rpm's and speed you obtain wide open trimmed up just before it starts porpoising. Also note if you feel boat break free from suction on water and rpm's rise as you trim up. This is info you need to make a decision on prop or look at other things.
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All good points. My advice was assuming that the motor is at correct height. If you can get bow up enough (without porpoising) with only motor trim that would be ideal.
Depending on degree of v in bottom you may or may not need tabs to control chine roll. My point is, if you don't need tabs to get the performance it's one less thing to deal with.
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Appreciate the replies. I'm going to try these out
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What RPM are you turning at max throttle and is it within manufacturers specs?
Are you trimming the engine? Trim engine in (down), give full throttle until the bow drops. Adjust your RPM to 4000 and trim out until the bow porpoises, then bump it back down a couple of bumps until it stops porpoising. This is your cruise speed. You will notice the bow spray move from the front of the boat to behind the console and at perfect trim, you will find it very easy to steer.
Next, advance throttle to full and trim out again, then in a little until you stop porpoising. This is your max speed and RPM should be within manufacturers specs.

You and your dog should be wearing pfds and one of you should have the lanyard attached to you. There is a generic book called boating basics that comes with almost every new boat. If you didn't get a copy, you can possibly download it from the coast guard. Good luck.
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All of these are good suggestions, but if the prop came with the motor, which I'm sure the Viper did, your pitch is probably right. Make sure you are trimming out appropriately.

If that is not your problem, your most likely cause of lower speed and rpms is gunked up spark plugs. The ETEC is a 2 stroke engine, and if you switch from one type of oil to another at any point, your spark plugs will get loaded with gunk. When that happens, several of your cylinders will start failing, and you will significantly lose power. Seems like that boat ought to be running between 40 and 50 mph, so this may be your problem. Could be that you put in a different brand of oil when you bought the boat.
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   JOHN C.
Been following all of the good suggestions...just thought about it---BEFORE THE ACTUAL SALE..'What did the previous owner say how the boat performed'??????? John Castelluccio, Jr.
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Spot on advice on all fronts!!!
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