sylvan 17ft issues

[bardfromedson]

i bought a 17ft sylvan and have a few issues i want to solve. it has a 115 optimax and also has a 6 hp kicker. its slow out of the hole with the stock prop(don't know the pitch) and it porposes pretty bad when i trim up to far. it is a lot faster when it porposes but is not a fun ride. if i trim it down to stop it from porposing it pushes a lot of water and i can't keep it above about 35mph. i think top speed is only around 43mph. i need a new prop for sure but don't know what to get. also wondering if a hydrofoil would help both getting out of the hole and porposing. any help would be great.

[Grizzled]

My guess is it came with a 19 pitch prop...lower pitch better hole shot...higher pitch better top end..i run a 19 pitch 4 blade steel prop on a 90 hp , on the back of a 16 ft lund...she gets on plane quick and tops out at about 42 mph...

[jjstar]

Getting a different prop with a different pitch will change your hole shot and your top speed depending which is more important you can get the appropriate one. Talk to a decent dealer and they can advise you.

I had a 175 merc and by changing the prop I increased top speed by 7-9 mph but then you also have to watch your RPM 's as the new prop turned faster and I did not want to rev to high and hurt the motor.

I also installed trim tabs. these removed all porpoising I had and made it easier to get out of the hole. They also made it easier to adjust the boat in different conditions in my mind allowing for safer boating. Personnally I would put trim tabs on any decent sized boat I have after using them once.

[Donny Bear]

I run a High five speed prop on my 125 merc on a 17.5 Lund couple up with the hydrofoil on the leg and she gives me a fast flat 43mph and amazingly enough I can troller down around 1.8 t0 2.2 mph the old power prop kept me over 3.5

[Tredeb]

Check the height of your motor when running on plane. The anti Ventilation plate on your motor should be at the surface of the water. If it is too deep , you will never get the boat to run properly. Most dealers mount the motor too low in order to reduce ventilation. I moved my motor up one hole (about 5/8") and it made about 200-300 RPM difference and about 4" of ride height at the transom. After that, I had to drop from a 19" to a 17" prop to get my RPM. Since I was over propped before, I didn't really notice a drop in speed.

Once you have the height right, check your RPM. You need to hit the sweet spot on your motor in order to get the most out of your rig. Do this with a typical load in your boat. Most dealers will let you try different props and exchange them for different pitches without extra charge.

Of course, Make sure your rpm is accurate, mine was out by about 300RPM last year. It turned out it was a poor connection in the switch on the tach. we moved the switch a few times and it smartened right up.

On most boating forums, hydrofoils are viewed as unneeded on a properly set up boat and Trim tabs are viewed as good additions to almost any boat.

Lastly, use a GPS for speed. You can find prop calculators if you do a web search, from there, you can see how fast your boat should be going. Typical values for prop slip are around 10%. You have to enter your RPM, pitch, and Gear ratio.

FWIW, i have an Alumacraft Trophy 185 w/ a 150 hp Etec.

[bardfromedson]

i found a product on cabelas.Nauticus Smart Tabs™ - Self-Adjusting Trim Tabs for 130 bucks. will these work or do you need the pricy hydrolic/electric type tabs? also, i have never done it so i have to ask. how hard is it to adjust motor height?? my boat is in storage so i can't look at where its set. anyone else out there with a sylvan/ smokercraft with porposing issues??

Originally Posted by Tredeb

Check the height of your motor when running on plane. The anti Ventilation plate on your motor should be at the surface of the water. If it is too deep , you will never get the boat to run properly. Most dealers mount the motor too low in order to reduce ventilation. I moved my motor up one hole (about 5/8") and it made about 200-300 RPM difference and about 4" of ride height at the transom. After that, I had to drop from a 19" to a 17" prop to get my RPM. Since I was over propped before, I didn't really notice a drop in speed.

Once you have the height right, check your RPM. You need to hit the sweet spot on your motor in order to get the most out of your rig. Do this with a typical load in your boat. Most dealers will let you try different props and exchange them for different pitches without extra charge.

Of course, Make sure your rpm is accurate, mine was out by about 300RPM last year. It turned out it was a poor connection in the switch on the tach. we moved the switch a few times and it smartened right up.

On most boating forums, hydrofoils are viewed as unneeded on a properly set up boat and Trim tabs are viewed as good additions to almost any boat.

Lastly, use a GPS for speed. You can find prop calculators if you do a web search, from there, you can see how fast your boat should be going. Typical values for prop slip are around 10%. You have to enter your RPM, pitch, and Gear ratio.

FWIW, i have an Alumacraft Trophy 185 w/ a 150 hp Etec.

[Shmag]

Is this a new boat??? I am thinking more on the lines as tredeb that maybe the motor is not set right. I think the fin (plate) above the prop should be somewhat flush with the bottom of the boat. You don't need it in water to check this. Just lower your motor all the way down and see where abouts it sit's compared to the bottom of the boat

[Tredeb]

Very easy to adjust your motor height with the boat on the trailer if you have a tongue jack. If not, you can use a floor jack.

You will need two people. One to steady the motor and one to run the jack.

If you are trying to raise your motor,(most dealer setups will need the motor raised not lowered) start by lowering the tongue on your trailer a bit to give yourself some room to crank it up.

Next, put your motor in the down position, and put some wood blocks under your skag. Crank up the jack so that the skag is resting on the blocks.

Now loosen the mounting bolts for your motor. Two will be in slots and two will be in holes. just loosen the slot ones and remove the ones in the holes.

Now you will have to hold the motor steady while someone raises the front of the trailer. This will lower the back of your boat allowing you to put the bolt back in on the next set of holes.

Tighten everything up and you are done.

I did this with my 150hp and it barely left a mark in the block and it was easy to hold steady. As mentioned, moving my motor up one notch made 3" to 4" difference in the depth of my leg in the water. A good starting point is having your Anti Vent plate even with the hull, but most boats will handle the plate being 1" to 2" higher than the bottom of the hull without problems.

The final thing to check, is the loading of your boat. I believe porpoising occurs when the motor/prop can no longer lift the front due to cavitation or loss of horsepower. If you lighten the nose, you can reduce this. Or maybe it is when the front is too light, I can't remember, and I never had this issue with mine so I am not sure. I do know you can affect it by moving weight around. Trim tabs will help as they hold the front down and raise the rear.

I think on small boats, the Smart tabs are the way to go. There is a lot of info on tabs on the web.

[bardfromedson]

thanks for the info. i think i will start with adjusting the motor and changing props. i like the trim tab idea but i put a ladder on the back and i dont think i can fit both. if adjusting the motor doesn't work i guess the ladder isn't going to stay on.
QUOTE=Tredeb;308166]Very easy to adjust your motor height with the boat on the trailer if you have a tongue jack. If not, you can use a floor jack.

You will need two people. One to steady the motor and one to run the jack.

If you are trying to raise your motor,(most dealer setups will need the motor raised not lowered) start by lowering the tongue on your trailer a bit to give yourself some room to crank it up.

Next, put your motor in the down position, and put some wood blocks under your skag. Crank up the jack so that the skag is resting on the blocks.

Now loosen the mounting bolts for your motor. Two will be in slots and two will be in holes. just loosen the slot ones and remove the ones in the holes.

Now you will have to hold the motor steady while someone raises the front of the trailer. This will lower the back of your boat allowing you to put the bolt back in on the next set of holes.

Tighten everything up and you are done.

I did this with my 150hp and it barely left a mark in the block and it was easy to hold steady. As mentioned, moving my motor up one notch made 3" to 4" difference in the depth of my leg in the water. A good starting point is having your Anti Vent plate even with the hull, but most boats will handle the plate being 1" to 2" higher than the bottom of the hull without problems.

The final thing to check, is the loading of your boat. I believe porpoising occurs when the motor/prop can no longer lift the front due to cavitation or loss of horsepower. If you lighten the nose, you can reduce this. Or maybe it is when the front is too light, I can't remember, and I never had this issue with mine so I am not sure. I do know you can affect it by moving weight around. Trim tabs will help as they hold the front down and raise the rear.

I think on small boats, the Smart tabs are the way to go. There is a lot of info on tabs on the web.[/QUOTE]

[Chris K]

Gentlemen, I don't really know how to say this properly, but there is no need for trim tabs on a recreational fishing boat. I am not trying to offend your opinions on them, but from my experiences from working in the marine industry at a corporate and dealership level, and from my boating experiences with more boats than I care to mention, a recreational boat for the freshwater recreational multispecies deep v hull should not need them. With a properly set up boat on a well designed hull, it is not needed at all. As well, hydrofoils won't do you much good either in the speed department. They can help from blowing out and allow you to run a taller prop, but in my opinion and in practical usage, I don't feel that they are a real solution to a problem, just a bandaid. Raising your motor up or down and finding the right propeller is the solution. Props for speed and bow lift are three bladed props. Three blades run more efficently, and then four blade and five blade props. A 4 or 5 blade prop can be better out of the hole, and let you run a higher pitch, but is not usually the best pick for all around performance. They are a good choice for putting on while pulling skiers or a couple tubers, but I would switch back to a three blade for cruising. Changing pitches can allow you to troll slower, but my personal choice is to put a driftsock under the bow, clipped to the bow eye for slowing the boat down. I carry a couple of different sizes, and this works really well if you are not using a kicker, and it cuts down on surging from waves as well. If you are thinking of running a stainless prop from Mercury, they have a wonderful selection for all applications, and some dealers have blue demo props for testing before you buy to see what works best for your boat. Generally speaking 3 bladed props are the norm, and obtain the best speed a bow lift. A Lazer 2 or a Vengeance is where I would start with a 19 pitch stainless, and then go from there. Going up a pitch generally changes things by 150 rpm's, and going up two pitches, from say a 19 to a 21 will generally be around 300 rpm's. The same applies the other way going down in pitch, but can vary some from different prop to prop and the diameter of the blades. Mercury also has a PTS venting system where you can open the vents or keep them closed to fine tune your holeshot. Weight distribution also plays a part, and from a full gastank with a full load and full livewell, you run a lot differently than empty. When testing differrent props keep your variables as close as possible so you can see what performance differences there are from prop to prop, and pitch to pitch. It's a science, but when it's dialed in, it's worth the work. Here is a link to Mercury's prop selector:

http://sites.mercurymarine.com/porta..._schema=PORTAL

Chris K

[Tredeb]

Originally Posted by Chris K

Gentlemen, I don't really know how to say this properly, but there is no need for trim tabs on a recreational fishing boat. I am not trying to offend your opinions on them, but from my experiences from working in the marine industry at a corporate and dealership level, and from my boating experiences with more boats than I care to mention, a recreational boat for the freshwater recreational multispecies deep v hull should not need them. With a properly set up boat on a well designed hull, it is not needed at all. As well, hydrofoils won't do you much good either in the speed department. They can help from blowing out and allow you to run a taller prop, but in my opinion and in practical usage, I don't feel that they are a real solution to a problem, just a bandaid. Raising your motor up or down and finding the right propeller is the solution. Props for speed and bow lift are three bladed props. Three blades run more efficently, and then four blade and five blade props. A 4 or 5 blade prop can be better out of the hole, and let you run a higher pitch, but is not usually the best pick for all around performance. They are a good choice for putting on while pulling skiers or a couple tubers, but I would switch back to a three blade for cruising. Changing pitches can allow you to troll slower, but my personal choice is to put a driftsock under the bow, clipped to the bow eye for slowing the boat down. I carry a couple of different sizes, and this works really well if you are not using a kicker, and it cuts down on surging from waves as well. If you are thinking of running a stainless prop from Mercury, they have a wonderful selection for all applications, and some dealers have blue demo props for testing before you buy to see what works best for your boat. Generally speaking 3 bladed props are the norm, and obtain the best speed a bow lift. A Lazer 2 or a Vengeance is where I would start with a 19 pitch stainless, and then go from there. Going up a pitch generally changes things by 150 rpm's, and going up two pitches, from say a 19 to a 21 will generally be around 300 rpm's. The same applies the other way going down in pitch, but can vary some from different prop to prop and the diameter of the blades. Mercury also has a PTS venting system where you can open the vents or keep them closed to fine tune your holeshot. Weight distribution also plays a part, and from a full gastank with a full load and full livewell, you run a lot differently than empty. When testing differrent props keep your variables as close as possible so you can see what performance differences there are from prop to prop, and pitch to pitch. It's a science, but when it's dialed in, it's worth the work. Here is a link to Mercury's prop selector:

http://sites.mercurymarine.com/porta..._schema=PORTAL

Chris K

I agree with Chris.

I re read my post and it seemed like I was recommending smart tabs. I was not, I was tryint ot answer the question of hydraulic tabs or smart tabs. I believe that if your boat is setup properly, you will not need them. There may be situations where you could see a benefit, but I doubt that you would "need" them.

The only reason i looked into them at all was in order to lower my planing speed. My boat tends to be on and off plane right at the speed where people like to waterski. It becomes quite the task to maintain speed when your boat is on and off plane throughout a ski. I haven't towed many skiers with my boat, so far, so this summer I plan to move some weight around help me either stay on plane or off while skiing.

[bardfromedson]

does raising the height greatly effect the time it takes to get on plane? im starting to think i may be quite low because i talked to a guy with an identical boat and motor setup last year and all he said he did was change props and he was running about 58mph.no porposing or lag out of the hole. i don't recal the pitch but i think it was a 3 blade stainless. i think he also had the motor mounted higher than mine.

[Topwater]

Originally Posted by bardfromedson

im starting to think i may be quite low because i talked to a guy with an identical boat and motor setup last year and all he said he did was change props and he was running about 58mph.

Your freind sounds like a fisherman alright! 58 mph. LOL

[seahawkfisher]

it may be used as a "bandaid" but i put a "good" hydrofoil (no drilling req'd) on my boat and it elliminated all cavitation, at any speed. i have an old tri-hull and without the foil, i had to stand up to see past the bow of my boat at lower speeds before it would get on plane; with it, holeshot is much better, and the ride/control is far more comfortable. if you don't have a ladder to get into the boat after a swim/wakeboard, it makes for a great step too.
cheers

[barbless]

I have a 17ft. Sylvan Pro Fish, Yamaha 150 VMAX 2 stroke and a six horse kicker. Had the same problem. Had to stand up to see over the bow, took forever to plane, real crappy at slower speeds. Put what looks like a whale fin on the leg of the motor right on the cavitation plate and presto instant hole shot and on plane in seconds. Not sure what top speed is, but it's fast enough for me. Slow speeds are not scary any more cause I can see over the bow. Putting the fin on took about 15min. My motor is at the right height. I got a good deal on this boat when I bought it because I think the guy who sold it thought there was something wrong with the boat. Works great for me now.

[bardfromedson]

Originally Posted by Topwater

Your freind sounds like a fisherman alright! 58 mph. LOL

sorry ...48 mph

[bardfromedson]

picked up the boat last night. it has a 19 pitch prop. the plate is pretty much flush with the bottom of the boat but i have room to move it up. i may try moving it up one hole . the prop is in a little worse shape than i thought so i want to try a new one before changing anything else. is ecko marine a good place to take a boat? i want to be able to try a few different props in a day without having to drive 50 miles back and forth to water and the dealership. also any idea if they would have trim tabs?

[Waxy]

I agree with ChrisK and others.

A properly set up motor and the right prop should take of it - no need for trim tabs or hydrofoils. That said, if a hydrofoil of some kind works for you, there's no reason not to keep using it, every boat is different.

For props, I'm not a big fan of the Lazer series from Merc, I think you'll get much better results with the Tempest or Tempest Plus. The Tempest Plus is a great all around prop, and gives you the PTS system to help dial in the holeshot.

I'm currently running the Tempest Plus, and it's great all around, especially if you adjust the PTS system. No prop is perfect for all situations though, and I'm actually looking for a second prop, likely a HighFive, for the rough water days and the times when more control and steady speeds are critical.

The best advice is to try a bunch of them, 3, 4 and 5 blades and various pitches, and see what you like best.

Waxy

[Tredeb]

Originally Posted by bardfromedson

picked up the boat last night. it has a 19 pitch prop. the plate is pretty much flush with the bottom of the boat but i have room to move it up. i may try moving it up one hole . the prop is in a little worse shape than i thought so i want to try a new one before changing anything else. is ecko marine a good place to take a boat? i want to be able to try a few different props in a day without having to drive 50 miles back and forth to water and the dealership. also any idea if they would have trim tabs?

Let us know what you end up with once you get out on the water.

[Cam-hunter]

Wow great info here guys I have a Sylvan 17 and i am ready to burn it great info here maybe this will solve my issues as well+
All mine will do is Plow almost impossible to get it to plane
I would never buy anything from Ship wreck ever again

cam

[bardfromedson]

Originally Posted by Cam-hunter

Wow great info here guys I have a Sylvan 17 and i am ready to burn it great info here maybe this will solve my issues as well+
All mine will do is Plow almost impossible to get it to plane
I would never buy anything from Ship wreck ever again

cam

where did they mount your motor? mine was the second from the top mounting hole. i only had room to drop it one hole which i did. its only about 1/2 an inch from flush with the bottom of the boat now. picking up some new props and going to try it on wabamun tommorow.

[Cam-hunter]

second hole from the top as well

[Cam-hunter]

hey anyone know if there is a fuse for the power lift on the motor went out to look at things and there is lots of power in the boat but nothing when i try to lift the motor all 3 switches tried and nothing?

Cam

[Buckhead]

I own a Sylvan 17' as well.

So far, I have only run the standard Mercury BlackMax 3 blade aluminum props. The outboard is set at the 2nd hole from the top which puts the cavitation plate about level with the bottom of the hull.

I have not experienced any of the problems that you fellows have.

For general use I run a 19 pitch prop. This gives me a good holeshot and top speed. With a full load of people and gear - top speed is 43-45 mph. Stays on plane fine as low as 24 mph.

For pulling skiers and if I am going to do a lot of trolling - I switch to a 17 pitch. Great holeshot and not much loss in top speed, 38 - 40 mph. Also, trolls down to 1.5 - 1.8 mph. Planes good as low as 19 mph.

The boat will porpoise at higher speeds if I do not trim properly and am carrying an unbalanced load - usually too much weight in the back of the boat. I have not really had any problem getting the boat to stop porpoising by adjusting the trim.

[bardfromedson]

just got back from the lake. i tried an aftermarket brand of props. clones of the merc aluminums. that along with lowering the motor helped out quite a bit. 39-40mph with the 17 pitch(5500rpm) and 42-43 with the 19(5400rpm) still porposis a little but i have to trim a lot higher for it to happen. also had 2 other guys and the dog in the boat( about 700 pounds) along with all my fishing gear and the kicker so i was quite happy with how its running. tryed later with only 2 of us. only lost about 1 or 2 mph with the extra guy in the boat. the only bad thing is it will not get up on plane with 3 people if one guy is in the back of the boat. once on plane it handled about the same if a person was in the back or the front. planes a lot better than last year as far as plowing water. thanks for all the help people gave on here. would recomend trying this (lowering the motor) if your having the same issues.

[Marlin07]

The new hair cut's on the guy's should raise the top end speed at least a mile or two. If I'm not grounded when the wife get's home we should hit a lake one of these day's

[Tredeb]

You really need to see where your motor is sitting w.r.t the surface of the water when your boat is on plane. Your Anti Vent plate should be at the surface of the water. Most boats have the motor too low from the dealer so it won't blow out in the corners.

My boat gained 300 RPM when I raised the motor one spot. Just use the bottom of the boat for a starting point. You really need to see where your motor is when you are on plane.

Here is what I am talking about.
http://www.propgods.com/forum/Default.aspx?g=posts&t=98

[mike.elmes]

The majority of boats that have a kicker on the back have a porpoising problem.
It is all about weight distribution. Most 4 stroke kickers are adding 100 pounds or more to the back end of the boat. The best way to fix this is to add trim tabs.....or have your wife's fat friend sit up front.

[bardfromedson]

the kicker may be adding to it but when i add weight to the front it doesn't fix the problem. as far as trim tabs go i don't think i have the room with the kicker mounting plate on one side and the swim deck on the other. its mounted as low as it can go now and is just above the bottom of the boat. every dealership that i have talked to say that trim tabs are not the answer for a smaller boat. they may fix the problem but the real problem is with where the motor is mounted. same thing with the whale tails. unless your pulling skiers and can't get on plane fast enough they are fixing a motor mount problem. all i know is its a lot better now than when i started.

[Waxy]

Originally Posted by bardfromedson

the kicker may be adding to it but when i add weight to the front it doesn't fix the problem. as far as trim tabs go i don't think i have the room with the kicker mounting plate on one side and the swim deck on the other. its mounted as low as it can go now and is just above the bottom of the boat. every dealership that i have talked to say that trim tabs are not the answer for a smaller boat. they may fix the problem but the real problem is with where the motor is mounted. same thing with the whale tails. unless your pulling skiers and can't get on plane fast enough they are fixing a motor mount problem. all i know is its a lot better now than when i started.

I completely agree, trim tabs are not the answer IMHO.

Waxy