& How To Check!if(typeof __ez_fad_position != 'undefined'){__ez_fad_position('div-gpt-ad-bornagainboating_com-leader-3-0')}; Aaron has been working in the Marine Industry for over a decade and holds certifications for Yamaha and Mercury Marine. could a few different probs. Then the bow is extremely light and the stern is super heavy. Once it is porpoising the only way to stop the … When the boat experiences a low trim angle as part of the bow-down cycle, the nose starts to dig in, leading to further damage. Boat porpoising badly above 27 mph. Like what prop, How high is the engine off the transom. maximum efficiency when it comes to getting better fuel economy as well! Thread starter Keller1490; Start date Aug 20, 2011; Status Not open for further replies. I always store and trailer the boat with the plug out so there was no water in the boat. There have been reports that porpoising can be eliminated by adding trim tabs. Such a boat as you describe, 6 metres 150 hp, will cruise comfortably at 25 knots, and top speed not far from your 40 knots. well I'm at the point of seriously considering buying a stainless prop....except that I have no idea which one to get. While they are essential for boat operation, they also need to be in the right position in order to complete their job. I was told top speed was 50 for my boat which has the Mercury 210 Sport Jet. Topic author. A round bottom can do what your saying and is a simple thing to eliminate, as far as a cause. When you go to start the engine, it simply clicks. If you’ve been through this experience, you know how scary it can be, and you want quick results. Yet, this vital... Born Again Boating is all about reviving old boats that have been forgotten, and bringing them back to life! The severity of boat porpoising can range from a mildly uncomfortable ride to downright dangerous, depending on the conditions. Boat will only cruise between 25 -27 mph. Straight line of hull intersects lower at top of water screen intake. & How To Check! 05-14-2004, 06:47 AM. There aren't alot of those hulls around but I'm sure we can help, But some more info will help. This site is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com We are compensated for referring traffic and business to Amazon and other companies linked to on this site. This will sound as though you are really revving up because the prop cannot stay 100% in the water to engage and reduce the RPM to the correct levels, etc. Is that the only speed range that you have the problem? How to stop your boat from porpoising. It occurs when planning across smooth water.if(typeof __ez_fad_position != 'undefined'){__ez_fad_position('div-gpt-ad-bornagainboating_com-medrectangle-3-0')}; Basically the bow of the boat just bounces up and down on top of the water. It could also stuff, which means that it trips over the bow. There's a point where speed overcomes the weight tendency to keep the hull planing flat we never could get that thing going very well. Porpoising Verb To move through the water like a porpoise, alternately rising above it and submerging. It is not uncommon for him to own and be working on at least three different boats at any given point in time! The good news gets back to tabs, because a bit of down tab holds the bow down, and you can use both engine trim and trim tabs to adjust for the " perfect ride " … Probably, you have a motor that’s simply mounted too low. The plug being in is not the issue. Seriously though, porpoising is something we get quite a few calls on, and it is one of those terms that you hear about mostly with regard to RV’s. These washers are there to space the recess that is in the plate for the flat faced counter sunk machine screws. How to Trim Tabs Help Stop Porpoising Some boats demonstrate porpoising (cyclic rising and falling of the bow). ... (propeller), raising the engine allows the bow lift proponent in thrust to overrule the leg drag and keep the bow up -no porpoising. To recap. When the lift is generated at a high trim angle or low dead rise, it leads to an unstable load on all of the lifting surfaces. If you have one of these 3 problems, then it’s worth buying an outboard motor hydrofoil. I haven't tried yet, but I'm guessing more trim is only gonna make it worse, … By altering the weight balance of your boat, you can affect the trim angle and speed when porpoising begins. i have a 24" raker gathering dust in my garage if you're interested. As someone that spends a lot of time on the water, you might wonder why boats porpoise. Porpoising begins as you motor picks up speed and raises your boat's hull from the water, reducing the amount of hull in the water -- which means there's too little hull in the water to support the boat. The anti-cavitation plate is your indicator in relation to the hull. If 20 litres of fuel in the anchor well makes a significant difference to the porpoising behaviour, I'd say the centre of gravity is too far toward the stern than optimal. IMHO that's where the porpoising is coming from. With the motor trimmed all the way in (bow down) the boat travels quite well but when I start to trim the bow up so I have less hull in the water my speed starts to increase but the porpoising starts. I think thats the problem with my checkmate. the battery originally was in the back, the more weight I put forward the better it got.....but now there's nothing else to put in front....fuel tank won't fit, and I'm not too fond of adding weight to the boat....I'll try playing aroung with different trim positions and height of the outboard...except it's just starting to cavitate around turns now...is there a type of propellor that is less prone to cavitation (I'm using an aluminum prop now) so that I can raise the motor??? Request The Next Technician's Tuesday Video Topic! Yes, trim tabs will knock down the porpoising issue and you can still adjust motor trim as well. Trimmed all the way in, the boat does not get on plane as quick as it should.

Once on plane, still trimed in, the bow is plowing down, as would be expected. Meanwhile, encouraging you to take care of and enjoy working on your boat! Was wondering if there are any suggestions. Porpoising is front to rear bounce; the front hits a bump, then the rear hits the bump, and they both bounce independently of each other, creating an oscillating motion. Some people feel that it is an unattractive method to correct hull performance, but it will offer you a more comfortable ride in the short term. Tuff to steer but I will adjust the tab. I highly recommend Mikes foils and hes easy to work with. This reduces drag on the front, which partly causes porpoising. View Full Version : how do I stop my boat from porpoising? You can have more people stand in the bow of the boat to get the bow to sit down in the water, then have everyone sit down evenly around the middle of the boat.if(typeof __ez_fad_position != 'undefined'){__ez_fad_position('div-gpt-ad-bornagainboating_com-box-4-0')}; Same with the bow being heavy. I have heard a rulle about raising motor for so many inches back from transom. The distribution of all the people and gear on the boat is vital for this reason. When trimmed, the angle of the prop is trying to force the boat's bow up, and then the hull weight brings it back down - " porpoising ". If you want a motorboat that handles its best, you want it to run parallel with the at-rest waterline. The boat did not do it before I took it into the shop. Does YOUR Boat Have The Right Propeller? Funny thing is it runs no diffrent with the smart tabs in play or pulled all the way up now. Anti-cavitation plates are found on most outboards. Causing the bow to ride high, and make the boat porpoise once you are at wide open throttle.if(typeof __ez_fad_position != 'undefined'){__ez_fad_position('div-gpt-ad-bornagainboating_com-banner-1-0')}; There are some other indications that your motor height is too low. As an example, if you make a change to the prop to add more aft-Lift, you effectively alter the dynamic balance of the hull. It’s making your day boating a little less enjoyable. Check out Ron Hills props he sells on ebay and maybe try a yamaha style prop. Porpoising is a common problem that many boat enthusiasts experience on calm waters. Effectively what is happening is as follows: The boat comes up on plane and begans to accelerate. I had the same problem with my 16' Carlson which is I think is basicly the same hull design, to correct the problem I blue printed the bottom of the hull, the last 4 feet of it or so, I also took out the wedges and man what a difference it made, no porpoise and much faster top speed. The jack plates lift the motor out of the water higher.if(typeof __ez_fad_position != 'undefined'){__ez_fad_position('div-gpt-ad-bornagainboating_com-large-mobile-banner-1-0')}; By raising the motor, you receive less drag on the boat and the lower unit. If you are still experiencing porpoising even with your trailer loaded properly then you need to make sure your ball mount sits at roughly the same height as your trailer coupler when level. If it is below the water line, it is going to pull the back of the boat down into the water. I could care less about holeshot and acceleration ( Ihave no problem getting up on plane), I just want nice cruising at half throttle and above, with the best available top end...I understand that the best way to figure this out is to try a bunch of different props, but I don't have that luxury, so with your help I'll try to make an educated guess as to what buy. What is the designed max-speed of the boat? If you have difficulty reaching your top speed, you might have trouble with the motor height. Additionally, the hydrofoil should offer a two or three mph boost at cruising speeds. (30 mph) Backing the throttle off will stop the porpoising. Home > General > How to stop your boat from porpoising How to stop your boat from porpoising. Once the boat. My boat runs it's fastest with the motor trimmed out until it porpoises then I add just enough tab to kill it and she skates along perfectly. This is a phenomena which is specific to cars which rely heavily on ground-effect to create downforce. The jack plate enables the outboard to offer optimum performance while traveling in shallow water. Another potential cause for the porpoising is the movement of water in the tanks. Start tilting the engine down slowly until the consistent RPM and maximum speed is reached again. Many of us know one way to stop it, trim down…way down. Since I've added the droop and some wedging my boat rides great up to 55mph-60mph but just as my secondaries begin to open up and start to really haul a$$ the boat … Steps to Take to Prevent Porpoising. You can often tell that an outboard is too low if you are experiencing sluggish speeds, poor handling, excessive spray, porpoising, or even water pushing up into the cowling. Basically, porpoising is the word used to describe a bouncing boat -- when the boat is bouncing from hull or trim combination's and not the water. on my little 14.5' Ebko...I already have the engine in the minimum trim position (manual trim, first hole, pin closest to transom), I put the battery in front of the boat, but still as sson as I hit 38~39 mph it starts to porpoise. There are a few plates available for this, but our local dealer suggested just a couple inch wide flat piece of aluminum mounted to the transom on each side. When the trim is at a high angle, porpoising is more likely to occur. Check the bottom to make sure its flat. How to stop porpoising? As to... Signs of a Bad Outboard Water Pump & Maintenance Tips. The plug being in is not the issue. cavitation plate 2" below the bottom? There are also instances that the foils reduce side-to-side rocking with a beam sea.if(typeof __ez_fad_position != 'undefined'){__ez_fad_position('div-gpt-ad-bornagainboating_com-large-mobile-banner-2-0')}; However, the hydrofoil isn’t necessary to stop the boat’s porpoising. October 20, 2010 ebuyersworld Leave a comment Go to comments. when you say you blueprinted the bottom of the hull, what do you mean?? Weight, wind speed, boat speed, engine rpm and wave heights has no affct on reducing or increasing the amount of porpoising. Any time that the hull experiences a change to the dynamic balance of forces, there will be residual longitudinal instability. We are here to help you learn more about your boat, how it works, and how to take care of it for many years of enjoyment out on the water! Boat ran same speed but again no porpoising unless he moved up but it was very easy to control. Once you start porpoising it will continue until you turn or slow down. These plates are flat and found on the lower unit. That’s a very brief, basic accounting of symptoms, but you’ll usually find at least one of these symptoms if your motor is too low. When the outboard kicks up excessive amounts of water, you are looking at a tell-tale symptom of a motor that’s mounted too low. "the boat began to porpoise badly" or in our case to drive along the road, alternately rising and diving. If your alum. This action further changes the range and speed of the hump zone, which should eliminate the porpoising effect. Add trim tabs. ... the weight load can still stop the bow from lifting and thus prevent the boat from getting on plane. A higher deadrise hull is less susceptible to porpoising. If you lose control over the boat, there is a risk of structural hull damage, payload damage, and injury to the passengers. A hydrofoil literally lifts most of the boat out of the water. Consider changing the trim angle as you drive through the hump zone to keep your vessel under control.if(typeof __ez_fad_position != 'undefined'){__ez_fad_position('div-gpt-ad-bornagainboating_com-leader-2-0')}; We discussed weight distribution earlier. Marine Dynamics SR- XPI-1 Stingray Hydrofoil. I cannot trim up at all. As the motor is trimmed back, more and more of the boat comes out of the water. The smaller your boat is, the most of an impact you will see, especially if your boat doesn’t have trim tabs. To change the dynamic balance of the hull, you can adjust the propeller selection and we show you how in this article! The altitude of the boat on the water should change, causing a slight rise to the bow. The weather is clear, and the water is smooth—there’s nothing to stop you from having a blast! You’re on the water, the throttle is opened up….but you can’t keep the bow from bouncing around. Bigger trim tabs that can be controlled should put an end to the porpoising. Use a bit of down trim on the motor to stop porpoising. Changing out your shocks and sometimes your springs will usually diminish the problem significantly. If the boat is already back heavy. The problem is that … Porpoising may also occur when the trim on a boat is at an improper angle. Plus, when boats porpoise, there are many dangers to consider. You don’t want the boat to begin porpoising as a result of the changes. If your weight is distributed unevenly, you face a higher risk of porpoising on the water. This is a phenomena which is specific to cars which rely heavily on … Regarding this, will Trim Tabs stop Porpoising? Problem 1 – Your boat ventilates when the motors trim down. Are you trying to surpass that? Hi I own a Nitro 2016 Z20 and I have issues with the boat wanting to porpoise at speeds between 20-45 mph even with the trim set somewhat below halfway up. comes back down, the outdrive will once again push it back out of the water.. The tunnel in the front and flat in the back setup will send a load of air at your prop, which is probably why it is so deep. Plus, it is now operating at its maximum efficiency when it comes to getting better fuel economy as well! Get Your Own Born Again Boating Apparel! Although, it runs as smooth as silk at 50 - 70 MPH, trim at half way or a touch above but never higher. Porpoising, or the bow bobbing up and dow, is caused by over-trimming at cruising speed; there’s no longer enough hull in the water to support the weight of the boat. Easy way to stop porpoising. Place the motor into forward gear and apply throttle until you reach cruising speed. It should ski across the surface of the water whenever the boat is on-plane during operating speed. It looks like a perfect day for a cruise. Tuck the motors in a little more. I hope I can get more than 40 mph out of this boat (fastest I've ever been on water, other than a snowmobile)......these guys seem nice and it seems like they really want to help average joes like me....I'll let you know how it goes... i've had that kind of set up before the only thing that worked was a hy/foil good size one helped like you wouldn't believe! K. Keller1490 New Member. I haven't tried yet, but I'm guessing more trim is only gonna make it worse, help, Thanks! Adding trim tabs would be a big help in keeping the bow down and eliminating any porpoising that occurs. Problem 2 – The bow bounces up and down We encourage you to check us out on our YouTube Channel! Water is pretty heavy and once set in motion it tends to keep moving. Porpoising is when you are cruising and the bow of the boat starts bouncing up and down, progressively and rhythmically getting worse and worse. An outboard that is mounted too low will limit your boat’s optimal operation. Boat ran great! October 20, 2010 ebuyersworld Leave a comment Go to comments. Porpoising should not be a problem if properly designed, and there is always the option of trim tabs, which are probably a good … I can't get past 40 without bouncing everyone out of their seats. Click to see full answer. Yes, trim tabs will knock down the porpoising issue and you can still adjust motor trim as well. Trim tabs can’t make up for the reasons for porpoising, which include a hull with too much rocker aft, an outboard mounted too high, or props that create too much bow lift. You know that once you hit a certain speed, no matter how pristine the surface of the water, you are in … It's fine when going 20 km and under. By raising the prop shaft higher, you shift the Dynamic Configuration forward and further reduce the trim angle. Top. An incorrect propeller can also cause you to not be able to reach top-end speed as well! Porpoising is known as a cyclic oscillation of the powerboat in relation to pitch and heave, with sustained or increasing amplitude. I'm afraid to go any lower because it looks like the plate which the front two bolts of the trim plate go through, is bending. With a little weight distribution, you can create a positive effect on when and where the hump zone occurs. When your boat is porpoising at a certain speed, consider lowering the trim angle, using our directions above. Getting a Jon boat on plane. View Full Version : how do I stop my boat from porpoising? By altering the weight balance of your boat,... Clean hull bottom. This should completely eliminate or greatly reduce the problem. While it’s never fun to have a boat porpoise, the solutions to the problem are simple enough to implement. 2 inches below bottom of boat...I put a straight edge against the bottom, it's a tunnel that turns into a flat bottom, but there are two "hooks" about 1/8" tall that extend forward about 10", they're pretty flat, but do curve upwards about .050" across the 10" span....the bottom seems nice and stiff to me, no floor in the boat, the bottom IS the floor......any other info that may help?