can't get bow out of the water

[lingcod]

boat is a 2009 northwest jet 218 lightning. 2008 yamaha 150 with a 14 1/4 x 17 stainless prop. turn 5000 rpms at WOT. 35 mph GPS verified. problem I am having is that I cannot get the bow out of the water. boat entry at cruise and WOT os right under captains seat. I would like the entry area to be in the back third if the boat. This is with an empty boat. I know jack slitt about props and was wondering if there was something that can be done to allow for more bow lift while underway. also, cav plate is level with the bottom of the hull. will moving it up a hole help?

lingcod

 

[Ike-110722]

Re: can't get bow out of the water

DO you have trim tabs? Have you tried trimming the sterndrive out. What about weight distribution on the boat. Do you have a lot of heavy stuff up forward? like anchors and chain? Beer? etc.

Move weight aft.

trim the out drive out.

tilt the trim tabs up.

 

[lingcod]

Re: can't get bow out of the water

DO you have trim tabs? Have you tried trimming the sterndrive out. What about weight distribution on the boat. Do you have a lot of heavy stuff up forward? like anchors and chain? Beer? etc.
Move weight aft.

trim the out drive out.

tilt the trim tabs up.

trim tabs in full up position,motor trimmed out to almost the point of cavitation,nothing heavy in the front other than a 7 lb anchor. boat design is cockpit forward. .http://www.northwestjetboats.com/. look at the 218 lightning. as stated, this is an empty boat, no gear, no beer, just safety equip on board with 2 adults.

lingcod

 

[Tahsismech]

Re: can't get bow out of the water

where does the leg of the engine sit when boat is out of water with it trimmed all the way down. you may have to put motor a notch down. prop should be approx below hull. if it is then re power to a 200?

 

[Robbabob]

Re: can't get bow out of the water

You have most of the information we need, but we need a little more... review this sticky http://forums.iboats.com/showthread.php?t=287818 and fill in the blanks. Specifically, what is the max rpm range for your motor at WOT? I see you achieve 5000 rpm at 35 mph.

Also, what is your hull rating for max HP?

Once you give the rest of the info, you'll get better input.

 

[lingcod]

Re: can't get bow out of the water

You have most of the information we need, but we need a little more... review this sticky http://forums.iboats.com/showthread.php?t=287818 and fill in the blanks. Specifically, what is the max rpm range for your motor at WOT? I see you achieve 5000 rpm at 35 mph.

Also, what is your hull rating for max HP?

Once you give the rest of the info, you'll get better input.

yamaha says rpm range is 5000-6000

no idea what max hp rating for the boat is. there isn't a capacity plate on it. lots of guys put 200's or even 225's on these boats. I didn't cuz I already had a 100 hour 150 from my other boat that was wrecked. I would say the most common engine for most people on this style of boat is either the yamaha or honda 150

lingcod

 

[Robbabob]

Re: can't get bow out of the water

With the lower HP, you'll need to pitch down to allow your rpm to increase closer to the 6000 area. You'll see better hole shot and and improved planing.

Dare I say going to a 13P to solve your challenge? Seems drastic, so I hope a true expert will take it from here and provide better input. Your 150 will like the lower pitch a lot more, but I'm not so certain about the performance of the boat.

Good Luck!

 

[Frank Acampora]

Re: can't get bow out of the water

I have a Manatee Cuddy, 21 foot, with a 140. When I reinforced the transom I raised the engine about 1/2 to 3/4 inch, leaving the cav plate about 1 inch above the pad. I used to run at full out trim with a top speed of about 38. NOW, I can only trim about half way out, the boat sits on the water like yours does, and top speed is about 3-5 MPH less due to increased wetted hull area. If you can not use full out trim, then it is time to try lowering the engine a bit on the transom. If it is even with the bottom, perhaps 1/4 inch below it may help. If your prop is NOT cupped, cupping it will make it hold the water better and allow you to use more out trim.

This winter I will try to get around to lowering the engine on my transom to gain back performance.

Looking at the model: Did you convert it from a jet drive? In the photo, the jet powered hull rides in the same attitude as you describe. Perhaps this is a design element?

 

[wired1236]

Re: can't get bow out of the water

35mph with your bow in water? Seems awfully fast to me to be pushing a lot of water. If you're getting up to 35mph with a 150, your hull should be designed to plane out at that speed with no problem. We don't have your gear ratio but my guess is that's about the speed you should be getting from your boat at WOT and if that's true, my guess is that your are on plane as the boat was desinged.

Don't put your tabs all the way up but somewhere in the middle setting (assuming they were installed correctly). Look up the specs on your tabs to find the right setting, (you didn't say what type of tabs you have). You WANT the tabs to do their thing and put pressure behind your transom to lift your entire boat out of the water. Putting them all the way up lets the stern of the boat sit down and therefor more of the hull will be in the water.

 

[rallyart]

Re: can't get bow out of the water

Every picture on their website has the keel in the water under the drivers seat. It may be the boat's design. If they are looking at rough water ride or cornering those would be reasons to have a larger wetted area.

 

[steelespike]

Re: can't get bow out of the water

I'm not a prop pro but a couple of points;
It appears to me that with the motor,2 adults and a tank of gas your approaching 4,000 lbs.Not exactly a flyweight. I think one reason the rpm is low is the need to get the bow up.Have you tried putting your passenger in the stern just to see the results?
You might check that the throttle is opening all the way Don't assume because it is a newer install it is right.With the motor at the bottom of the rpm band I don't think it can develope the lift to get the bow up.Its possible 15" might improve lift and rpm gaining more than the 200 rpm per inch rule.
A prop with bow lift would help, someone here should be able to suggest a prop.
Some dealers will allow you to test props with the understanding your going to buy one, usually requires a large deposit.

 

[wired1236]

Re: can't get bow out of the water

See my edit.

 

[Dhadley]

Re: can't get bow out of the water

Looks like, as mentioned, you may be "fighting" hull design. With that much setback lifting the bow should be no problem. Also with that much setback you'll be able to mount the motor much higher than if the motor was on the transom. That alone will help get your rpm up with the current prop.

 

[Silvertip]

Re: can't get bow out of the water

What yamaha says wide open throttle SHOULD be is only part of the equation. What YOU actually SEE on the tachometer at wide open throttle with an average load is what is needed.

 

[lingcod]

Re: can't get bow out of the water

35mph with your bow in water? Seems awfully fast to me to be pushing a lot of water. If you're getting up to 35mph with a 150, your hull should be designed to plane out at that speed with no problem. We don't have your gear ratio but my guess is that's about the speed you should be getting from your boat at WOT and if that's true, my guess is that your are on plane as designed.

I have seen other boats of this design and they seem to plane out way aft of where I do.

Don't put your tabs all the way up but somewhere in the middle setting (assuming they were installed correctly). Look up the specs on your tabs to find the right setting, (you didn't say what type of tabs you have). You WANT the tabs to do their thing and put pressure behind your transom to lift your entire boat out of the water. Putting them all the way up lets the stern of the boat sit down and therefor more of the hull will be in the water.[/QUOTE]

Tabs are Bennett hydraulic tabs, dealer installed. they have the tab position indicator and if I have them in the middle I will really be digging the bow in.

What yamaha says wide open throttle SHOULD be is only part of the equation. What YOU actually SEE on the tachometer at wide open throttle with an average load is what is needed.

My OP stated I am at 5k per the tach at WOT and I posted later that yamaha says 5k-6k is operating range.

Thanks for all the help guys I may be more confused than when I first posted this but lets keep at it and maybe we can figure it out.

lingcod

 

[steelespike]

Re: can't get bow out of the water

Do we have any pictures of your boat underway?Do we know what prop,rpm and speed these other similar boats w 150s are are running at?Are they indeed higher in the bow?
Is it right; boat is 2850,motor over 400,close to 500 for a 4stroke 150.2 adults 280,
fuel about 600lbs for 100 gals?Guessing 6 lbs per gallon.?Close to 28ft overall length. Seems like a lot of weight to expect sprightly parformance.

 

[Robbabob]

Re: can't get bow out of the water

I understand your slight confusion; several are trying to help with valid directions and any one of their points could be correct. They are all items to be considered.

Your max rpm at WOT is 5000.
Spec for engine is 5000 to 6000

You need to get your engine operating closer to the max at WOT to get better performance. However, even at 6000 RPM, your HP may not be enough to get the performance you want.

Valid sugestions:
*Going with a lower pitch prop.
*Changing the height of the engine.
*Using a cupped prop (SS perhaps).

You have to know what "the others" are using in order to get their performance. You say you see others using a 150 Yamaha or Honda; if they get the performance, which prop are they using and what is the height of their setup?

If you feel everything with the engine and prop are set up and working properly, then perhaps it is the tabs to review. Tabman works for Bennet Trim Tabs and has been a wealth of information to many in this forum.

Let us know how it goes!