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| Just recently purchased a 03 Lund Explorer 1675 with a 04 60hp merc 4-stroke efi and it seems pretty slow to get on plane with the livewells full and 2 guys in the boat. I dont have a speedometer/gps so I cant tell you top end but guessing 25 to 30 mph. could i get betterhole shot with a different prop without sacrificing to much topend? or if you guys have any other options I'd like to hear them. |
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Posts: 4053
Location: Land of the Musky | My boat did the same and I have a 16.5 with a 60hp on it. Buy a Hydrofoil for your motor. Put mine on and it snaps right up now.
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Posts: 20281
Location: oswego, il | My boat took forever to get on plane. I bought the SE sport fin and it still takes longer than i would like with 3 people but it gets there alot quicker, when sometimes it would not get there at all. |
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Posts: 3518
Location: north central wisconsin | When looking at hydrofoils, would this SE sport be the one you guys would choose? I have seen some of the stainless versions that might create less drag on the top end(Cobra brand) and was wondering if anyone had any experience with them, or maybe even the non drill models(skeptical of a non drill fin with that type of torque on it, but wouldn't mind any and all input). |
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Posts: 3514
Location: Elk River, Minnesota | Hi Everyone,
Before I would go out and buy a hydrofoil, I'm curious as to what your "normal load" is when using the boat and what pitch and diameter prop you have currently on it. If you constantly have your rig weighed down with people, gear, livewell, etc, then I would bet going down 2 inches in pitch on your prop would make things perform better at all RPM ranges with maybe a mph or two loss on the top end. If the prop pitch is too high, getting on plane is much harder (especially with heavier loads), can cause porpoising due to too much pitch and not enough "umph" from the motor to keep the bow of the boat up. Going down in pitch is definitely a good move when loaded down....The reason being is that if you have that much load on your motor, you are forcing it to work harder (with the higher pitched prop), which will over time shorten the life of the motor. It is excess strain on all of the parts of the motor...not just the engine..
Many times, when you go down in pitch, you gain diameter...which means you have a bigger "ear" in the water, which results in more thrust (more surface area for water to grab).. It is very similar to what you see with the high-thrust motors like the yamaha T8 kicker, although the high thrust kickers have a very low gear ratio to turn those big ears.
A hydrofoil is designed to help keep your boat on plane at lower speeds. (why the ads always say you gain fuel economy) Many times, you will see them on under-powered boats because the motor on it's own is not strong enough to keep the boat on plane efficiently, and trimming up the motor is not an option due to porpoising (why the ads say you gain speed).
If the motor is reaching it's maximum RPM under your normal load conditions and you are still having issues of getting on-plane and staying there, only then would I consider a foil.
If your boat is a tiller-steered rig, I don't think you are too far off of your max HP range, so when adding people, gear, etc. will definitely slow the whole thing down from hole shot to top end. If the boat is console steering, it is well under-powered...a foil might be your only option in addition to a lower pitched prop.
No matter what you do, there will be a compromise involved of some sort. It is a matter of what you desire to get for performance out of your rig...
Good luck!!
Steve
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Posts: 4053
Location: Land of the Musky | I have the 300 SE on my boat. I do not know enough about props to comment but the physics of what Steve (VMS) says makes sense. I know if I got a performance prop I may not need the hydrofoil but never wanted to buy the better prop for the money my boat is worth and how much I use it. I got my SE300 in the Cabelas bargain cave for around $30 I think. My motor (lower unit) already had the pre-drilled factory holes in it so it was just a matter of measure and buy for me. |
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Posts: 1762
Location: Mt. Zion, IL | Look into the "Doel Fin". It is designed like an airplane wing so it will have the least amount of drag. Think about this....and i'm not brand bashing in the least but the sting ray looks like any schmoe could carve it out of wood. It is big and bulky and a chamfered edge is not very streamlined. If that were the case we would see planes and lower units that were really thick. The doel fin was designed by an aeronautical engineer and dad and I have had them on 3 boats.....mine even until we got a bigger motor. It is typically 35 plus stainless hardware. |
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Posts: 3518
Location: north central wisconsin | Thanks alot for the reply Steve(VMS) and also the nice email. Now, and not questioning you, but isn't an underpowered boat having trouble keeping the bow down? I thought the underpowered tiller rigs with alot of rear weight, needed more stern lift(bow down). I was just wondering this out loud just now, as I am considering raising the motor a hole or two in attempt to get the stern up better and possibly cavitate the prop slightly to get more rpm on take off...?.. I think it might have been you that told me holes drilled in the prop might help with this as well....
Has anyone checked out the new 15 pitch vengeance prop by Merc for the 90 four strokes?? Heard some have had decent success with them. Wonder if I should check one of them out(running Power Tech 16p semi cleavered right now) before drilling holes for a hydrofoil fin that I'd rather not have.
With that said, I have seen more of the hydrofoil fins on tiller rigs than on consoles with adequate power. When only looking at fishing boats(not wake boarding rigs), it is a pronounced difference and high number of whale tails that I see on tillers of all makes, especially the 18'ers with 90hp ratings. Will check out the doel fins now, also thought the Cobra looked to create less drag than some as well. |
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Posts: 3514
Location: Elk River, Minnesota | Hiya,
Reef, you are right on with your assessment of how many under-powered rigs perform in the tiller models. In the past years we have seen a massive influx of wider boats with a hull that is more of a deep-V (aluminum hulls) and thus heavier overall. The design is definitely smoother for the passengers in rougher conditions, but the handling characteristics (in general) decline since the boat rides lower in the water.
To me, the HP ratings on these boats are well below what they could be for decent performance. My hull (Alumacraft navigator 165CS) fits this category as well. So...what you mention is for the most part "spot-on" in that many tiller models have a hard time getting up on plane due to (best words I can come up with) stern-squat. All the weight is back there (battery, operator, 4 stroke motor, etc). What the fin does for these situations is create a larger surface on the anti-ventilation plate which then helps to push the stern up when trimmed down for hole shot. One thing must be kept in mind with these is that in order for them to consistently work, they must be in contact with the water....and many boats are set up to be this way for handling purposes, but may not be the most efficient set-up. When the boat is trimmed down, the front edge of the fin is directed toward the surface of the water, so more surface area forces the rear of the boat up.
If you think back about 10 years or so, many tiller model aluminum boats had very small v-shaped hulls to even flat across the back (like the Lund S-series of many years past). Those boats would pop up on plane easily, but if you turned, it felt like the stern was sliding sideways.
I suppose I should say this....before doing anything, check the placement of the trim-pin. Every boat has one, and most, if not all Trim and tilt models have them in the lowest (or most negative) trim hole. If your pin is NOT in that lowest position, move that first, and test. The idea being to get more negative trim where the lower unit looks like it "tucks under" the transom, which will help the stern in hole-shot.
Moving the motor up off the transom (I feel) is always a worthwhile thing to try...you have less lower unit in the water, which equates to higher RPM's. This usually works best with steel props, which flex less and usually have a better ability to get a bite on the water. BUT...every boat would perform better if the motor is mounted higher. It will in some cases allow the bow to rise less, and it may help to get more boat out of the water at planing speeds as well. The only way to tell is to try it...so it never hurts, and in many cases, you might get a good surprise too. What is interesting is that many of the larger deep-V walleye boats can have the anti-ventilation plate mounted around 2 inches ABOVE the lowest part of the transom. Reason being is as soon as the boat moves forward, water rises back up to fill the hole the boat made. There is a limitation to this, but in most cases, being in the 3rd hole up will still do well...even with an aluminum prop.
Steve |
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| vms how can I tell what my pitch & diameter on my prop is? I'm pretty sure it is stock but I didn't buy it new so I'm not 100%.
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| VMS - 9/6/2008 7:42 AM
Hi Everyone,
Before I would go out and buy a hydrofoil, I'm curious as to what your "normal load" is when using the boat and what pitch and diameter prop you have currently on it. If you constantly have your rig weighed down with people, gear, livewell, etc, then I would bet going down 2 inches in pitch on your prop would make things perform better at all RPM ranges with maybe a mph or two loss on the top end. If the prop pitch is too high, getting on plane is much harder (especially with heavier loads), can cause porpoising due to too much pitch and not enough "umph" from the motor to keep the bow of the boat up. Going down in pitch is definitely a good move when loaded down....The reason being is that if you have that much load on your motor, you are forcing it to work harder (with the higher pitched prop), which will over time shorten the life of the motor. It is excess strain on all of the parts of the motor...not just the engine..
Many times, when you go down in pitch, you gain diameter...which means you have a bigger "ear" in the water, which results in more thrust (more surface area for water to grab).. It is very similar to what you see with the high-thrust motors like the yamaha T8 kicker, although the high thrust kickers have a very low gear ratio to turn those big ears.
A hydrofoil is designed to help keep your boat on plane at lower speeds. (why the ads always say you gain fuel economy) Many times, you will see them on under-powered boats because the motor on it's own is not strong enough to keep the boat on plane efficiently, and trimming up the motor is not an option due to porpoising (why the ads say you gain speed).
If the motor is reaching it's maximum RPM under your normal load conditions and you are still having issues of getting on-plane and staying there, only then would I consider a foil.
If your boat is a tiller-steered rig, I don't think you are too far off of your max HP range, so when adding people, gear, etc. will definitely slow the whole thing down from hole shot to top end. If the boat is console steering, it is well under-powered...a foil might be your only option in addition to a lower pitched prop.
No matter what you do, there will be a compromise involved of some sort. It is a matter of what you desire to get for performance out of your rig...
Good luck!!
Steve
Steve I don't know what my pitch & diameter is, I generally fish 2 guys sometimes 3 from my rig generally I will only have the livewells full in the fall but I usually have way to much gear loaded in the boat because everyone always wants to bring all of their stuff. and the lund explorer 1675 is a tiller.
thank you |
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Posts: 3514
Location: Elk River, Minnesota | O.k...there will be two possible places to locate the pitch and diameter. It might be stamped on the side of the hub, or it might be located under the castle nut holding the hub on the shaft. Being it is a mercury motor, I am betting it is stamped on the side.
Hopefully it is there...then no messing with taking the prop off...
Steve |
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| steve the prop is stamped with: 48 73136A40 13P Guessing this means
48 diameter and 13 pitch. Does that sound right and if so would a different prop suit me better? |
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Posts: 3514
Location: Elk River, Minnesota | The prop is a 13 pitch, and I am guessing you are looking at a 10-1/2 inch diameter or so. If you can find one, I would try an 11 or 10 pitch prop and see how that goes. One good place to look would be on Ebay...lots of props and good prices as well.
Steve
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Posts: 2754
Location: Mauston, Wisconsin | http://boatpropellers.iboats.com/Mercury_Marine-Black_Max-Propeller...
Have fun!
Al |
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Posts: 1462
Location: Davenport, IA | Its definitely worth trying a hydrofoil. My Javelin bass boat gets on plane a little quicker with one. I lost no speed either. I don't need it with my current prop though. That is the se sport 300. I had a 2 piece attwood hydrofoil that looks like the doelfin on my alumacraft bass boat and I lost 10 mph and it took a lot longer to get on plane. But they're easy to install, so it is worth a shot. |
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| hydrofoils do help in a lot of situations. in a tiller it makes driving alone much better as u can keep the bow down. As far as drag there should be no extra drag with a hydrofoil at speed. If you are running wide open and your hydrofoil is still in the water then you have other problems. |
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Posts: 1762
Location: Mt. Zion, IL | the hydrofoil mounts to the anti-cavitation plate....I hope when you're running down the lake that it is not above water.....you will be paddling your boat soon if that is the case.... |
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| If your boat is set up in a manner that allows for best handling and overall top efficiency, the anti-cavitation plate SHOULD be at or even above the water while on plane. Most boats are not set up that way from the dealer. The reason being is the majority of the population does not tweak their rig for peak performance and the position the dealer mounts the motor is for decent handling without a huge amount of drag. That is why they usually put the anti-ventilation plate flush with the lowest part of the transom..but...that puts the anti-ventilation plate BELOW the water line as the boat is on plane...The water fills the hole the boat made immediately after the boat passes.
That is the main reason why a foil will only work if the anti-ventilation plate is in the water, or just skimming along the top of the water due to the lift Characteristics it supplies. It provides lift as long as it is in contact with the water.
If the comment was made with the thought of losing water pressure, one will not lose enough pressure to cause ANY damage or worse yet burn up the engine IF they stay within the designed bolt holes on the motor. When a jack plate is added...that is when water pressure can become an issue. |
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Posts: 388
| Before you change pitch, you need to check rpm at top end speed and see where it falls according to the specifications on your owners manual. If you can measure speed (preferable GPS) and rpm and put those stats on the baord, others with a similar rig can comment on what you can expect. Other thing to check is the height that the motor is mounted on, check that and put that info up as well. Others with 1675 Exploreres can comment.
I had a 60HP that was a real dog getting out of the water. I installed a fin and this helped a lot. When I purchased my new rig, the dealer told me about the mounting height and what it does for motor performance. After learning this and looking at some pictures of my old boat, I noticed that it was mounted to the transom on the top hole of the motor mounting bracket which was undoubtebly too low. Too low and your boat will be very slow to plane and will never reach it's potential for top end speed. Too high and it will be prone to cavitate on hole shot and on turns. I would expect that your motor should be capable of 33 to 35 mph if set up correctly.
Edited by Yake Bait 9/20/2008 8:04 AM
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Posts: 4266
| Try a four blade prop. They are designed to get you on plane faster.
I'm getting a new motor, and I'm getting a four blade for sure. Besides getting up faster, they give you better and easier handling. I have a 75 tiller, and I need easier handling. A friend of mine runs a 100 HP tiller with a four blade prop, and it is so easy to maneuver his rig, it's unreal. My arm starts to hurt on long journey after 10 minutes with my stock prop. I'm going with four blades to take some of that load off. |
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Posts: 3518
Location: north central wisconsin | see new thread on smart tabs...
Edited by Reef Hawg 10/5/2008 8:04 PM
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