Getting To Plane

[shoot_my_boat]

Hey,<br /><br />I have a 1974 Bayliner Discovery with a Ford 302 5.0L V8 200HP & a Volvo Penta 270. My question is how fast should it plane with 4 adults in? This is my first boat to learn with so I destroy something nicer, so I unforuntly have nothing to judge against. I had a theory that the stern drive is not staying locked in place & pushing the bow up. The reason I think this is when going into reverse the stern drive pops up. This is a problem I am working on. If you have any suggestions about the lock, let me know. When we go full throttle the tach rises quick to about 3000 & slows until we plane. Once it planes it really moves!<br /><br />Thanks for any help!

 

[DJ]

Re: Getting To Plane

shoot,<br /><br />There are a lot of variables here. <br /><br />If anything, your outdrive would have a tendency to tuck under when power is applied. That is what you want. The more "tuck under" you get, the faster it will plane.<br /><br />What is your top, wide open throttle, rpm?<br /><br />If it is not within (too low) the range indicated by Volvo, then you are overpropped. Overpropping will slow planing time considerably.

 

[shoot_my_boat]

Re: Getting To Plane

My WOT should be at 4500RPM. But once on plane, it will go past that really fast! The prop on the boat I belive is a 15 15. I was told it would work pretty good for water skiing.

 

[DJ]

Re: Getting To Plane

It doesn't appear that your prop pitch is a problem.<br /><br />I do not know how big a Bayliner Discovery is. Bayliner has/had a habit of producing boats with marginal power.<br /><br />A 5.0L engine is not going to be real peppy in a 25' boat.

 

[shoot_my_boat]

Re: Getting To Plane

Sorry.<br /><br />I should have put more info in my first post. The boat is just shy of 17 feet. The current engine is not the original one. I don't know what kind of engine it was, but it had 160HP. I thought mabyee the weight of the upgraded engine was doing it but I can't imagine it being that much heavier.

 

[foxjohnc03]

Re: Getting To Plane

Did you replace the engine yourself? Do you know if it is a marine engine or a standard car engine? If your old engine was 160hp and was upgraded to a 200 then you will need a different prop. Try moving up another 2 inches.

 

[shoot_my_boat]

Re: Getting To Plane

When I got the boat it already had an upgraded engine. I don't know about the internals of the engine, but of course it has all the standard marine upgrades. Should I only raise the diameter & not the pitch or both?<br /><br />Thanks for the help...

 

[foxjohnc03]

Re: Getting To Plane

You should only have to change the pitch. Go up to a 17 or a 19.

 

[rogerwa]

Re: Getting To Plane

Every boat has a 'transition' phase from displacement to planing. How long does it take and does the nose go up a lot. With a V8 and a 17ft boat you should pop right up. The lower the pitch in prop, the faster it should plane so moving up in pitch is only going to slow the planing process. Since your RPMs shoot past the Recommended WOT, you are underpropped but still have the planing issue.<br /><br />If your planing is truly out of line, I would check your compression and give the beast a tune up to see if that helps. You might also try a doel fin to assist in planing.<br /><br />Another thing comes to mind.. outdrive gearset. If the engine was upgraded from say a big four or a six, did they make the proper gearset changes. I am not familiar with the Volvo ratios. while I don' think this would effect planing, it may effect getting the optimal performance out the V8.. <br /><br />Just my thoughts..

 

[shoot_my_boat]

Re: Getting To Plane

When we go full throttle like when water skiing, the bow pops really high up! It's a higher pitch than any other boat i've ever seen. It stays that way for quite a while. Someone usually has to get on top of the bow & sit on it. I have no idea about the gearing of the outdrive, but since it increased in power it just wouldn't reach a higher speed, right? I recently did a lot of maintance & it helped a little. What size of prop would you suggest for water skiing?<br /><br />Thanks

 

[rogerwa]

Re: Getting To Plane

Since your bow pos up really high, ensure your drive is tucked all the way in when starting off. If you are trimmed out at all it will effect you planing and point your nose north. If you are already trimmed all the way in, look at putting more weight up front, and again a doel fin will help in this regard.

 

[shoot_my_boat]

Re: Getting To Plane

Thanks for your suggestions!<br /><br />How do I make sure the drive is tucked in? I am having trobule with the lock on the stern drive as I said in my first post. Could this have something to do with it? I am new to boating & I don't know what a doel fin is. What is it & any idea how much it would be?<br /><br />Thakns....

 

[shoot_my_boat]

Re: Getting To Plane

Ok,<br /><br />I searched for doel fin & found out it's a hydro foil. Is doel fin a type of foil?

 

[Ralph 123]

Re: Getting To Plane

First, get yourself a copy of the book "Getting started in power boating" it will help you a great deal. It is a classic book that has served the test of time.<br /><br />Ok, now, do you have a "trim" switch that moves your outdrive up and down? "Tucking your drive in" simply means putting your drive all the way down - also called trimmed in - the drive is as close to the transom as it can get. That causes the stern to be raised and your bow to be pushed down. It gets you on plane the fastest way possible.<br /><br />The hrdo-foil or doel fin is like a whale tale that fits on the cavitation plate (middle) of your outdrive. It provides added lift for your stern to help you plane faster. (also called climbing out of the hole or the hole shot).<br /><br />Here is how you start off:<br /><br />You lower your outdrive(s) all the way down (same as all the way in) <br /><br />You smoothly advance to WOT (wide open throttle)<br /><br />when you get on plane you raise your drives (trim out) until you reach your max speed or begin to porpoise (drive he bow into the water) then you tuck the drive(s) back in slightly and reduce your throttle to you cruising speed. Tweak as necessary.<br /><br />Hope this helps - buy the doel fin - I use them and they work great make it much easier to plane

 

[rogerwa]

Re: Getting To Plane

Your reverse lock shouldn't be an issue. If anything if your drive isn't staying put, in forward it would help planing and not hinder it..<br /><br />AS far as prop is concerned, knowing how much past your WOT you can actually spin the motor with a normal load will help to set a baseline for your optimal prop. I would guess that you could swing a 17p and still have grunt for skiing since you probably have a v8 on v6 gears.<br /><br />The rule of thumb is that a step up in pitch reduces your RPM by ~200 RPM. If you can turn 400+ RPM over your rated WOT then you should be comfortable with a 17P prop. <br /><br />If planing is still a problem, after correcting trim usage, using a doel fin, and redistributing weight, then you could look a four blade prop. More holeshot, slight decrease on top end..