NR SeaHawk Porpoise Fix

[Blue Water 23]

Like I stated on a thread a couple of months ago I had no doubt that NR would take care of my boat. As it sounds like a lot of boats have been porpoising mine was too. Also, the T8 wasn't running right.

I took it in and the T8 and they found that I needed a new valve on the gas line. No problem and it was fixed.

The porpoising ended up also being an easy fix that some of you other SeaHawk owners might want to consider. The porpoising was a big problem and everyone had their own opinions on what is making these boats porpoise. I checked and my hull was fine, the engine was mounted properly, the kicker having a little drag wasn't the problem, the lip on the back didn't need to be bent down.

I know I will get flamed for this by people that know everything and question what others do to their own stuff but here it goes; A whale tail on the 150 Yamaha. It is just a little triangular/rectangular piece of metal that sits above the prop. It looks like a mini-trolling plate but it doesn't bend down. It sticks about 6 inches behind the prop, is about 10 inches wide, and parallel to the bottom of the boat. Like I said it looks like a little trolling plate but it doesn't bend down.

My boat gets out of the hole quicker, it doesn't porpoise, and it doesn't seem to bounce after the initial shock of going over a wave. It has the same or higher top speed but runs on plane at lower RPMs. It is a $50 part that completely helps the ride and performance of the boat. I am sure that some of you will argue that you shouldn't need to ad a part to get a $40,000 boat to ride better but it is the best $50 I ever spent. If any of you want an immediate fix to the porpoising problem and to get on plane quicker with the old style (2005 and older) off-shore brackets a whale tail is the way to go. Even with a back heavy load I didn't porpoise and I jumped on plane. This way I can use the trim tabs to balance out the load and trim the engine up when running to get better performance.

If you want to flame this save it and spend your energy doing something else. If you guys that have complained about this problem want a quick and easy fix then I can get you contact info.

Thanks to North River for getting me in and taking care of the few problems that I have had.

Jesse Eveland

[coffee-n-rolls]

Yup, I'm experiencing the same with my 21' scout. Did you get it at PPM?

Thanks
Tim

[Blue Water 23]

I got it at the North River/Yamaha repair place at the Charbaneau exit off of I-5. The guys name is Steve and he is great to work with. I got the number if you need it send me a PM, but I am sure you know the same place.

[Dipnet]

They are very knowledgeable and helpful there!!:bowdown:

Dipnet:)

[olybirds]

you'd think NR would give it to you, and eat the $50 for the fin if it fixes their porporsing problem.

But the main thing for YOU is that your boat ruins better now!

[Ak Seahawk]

Glad to hear something worked for you. Are you talking about installing the "Stingray" or the "SE Sport Hydrofoil" as shown in Cabela's or West Marine catalogs? Do you have any pictures of the installed whale's tail on your engine? Do you know whether or not it voids your engine warrany.

[Snowwolfe]

I used to own a Hewescraft 19 footer with a Yamaha 115 prop on it. It did the same thing. I added the same basic part and it cured the boat immediatly. Best bang for the buck out there.
The part will not void your warranty unless Yamaha can prove that part caused the problem. Other than drilling a couple of holes I dont see any issue it could create other than someone ramming there motor into a rock and breaking off the fin, then Yamaha could say you weakened it by drilling the small holes.
But then again, they would not cover it under warranty anyhow as you hit the rock.

[Ak Seahawk]

Thanks for the reply. Did you buy the Stingray or another model? there's a couple different models out there and I want to make sure I get the right one.

[BARCHASER]

I have an 18' NR Seahawk with a Yam. I had one of those wings on my old Bayliner and it worked. Maybe I'll put one on this boat also. Cheap enuff.

[Beefcake]

I'm guessing he got the "Whale Tail XL" (same one I have). For some reason, I couldn't find one locally (I had Clemens order me one, but I think they are available through Overtons). They are available in 3 different materials (plastic, aluminum, and stainless if I remember right). This is my 4th or 5th boat with some type of a hydrofoil, and I agree that it is money well spent.

My boat is a Duckworth with a similar offshore bracket to the older NR, and the other modification that I made was to add weight to the bow. This helps get on plane, but more importantly it balances the weight better for trolling. Before I added weight to the bow, I couldn't troll on a windy day because the bow got blown around too much.

[coffee-n-rolls]

Blue Water 23

I just purchased a 21'NR from PPM. After two outings, I noticed a severe issure with it porpoising. After reading about your problem, I contacted Scott at PPM and told him I was having the same proble. He said to bring it in and it would be fixed in about 5 minutes.

Apparently the trim tabs warp a little during welding, causing them to come up a small amount. Tracey (PPM employee), used a tool to bend the tabs down about 1/4 ". I took the boat back out the next day, and happy to say all the porpoising is gone. You may want to call them and have the same done to your boat.

PS. Don't watch him do it...just stay in the showroom and visit with someone. :jester: :jester: :jester:

Tim

[Tacklebuster]

Jesse,
That is great news. Forget the whole speach about "it should have come that way", I would have gladly paid the money to fix the problem. I had to get the new bracket because of the cracking that was going. I never had the porpoise problem. If so, I would be going the route you did to fix it. Truth be told, I like the old style bracket a little cause it was self contained and even if water was to get in there, it wouldn't get in your bilge. No worries about leaks around the bolt holes for the engine, and it was easy to determine where a water leak was coming from.

Hope to see you out this summer. I know you have baseball going but that May 1st butt opener is coming and I know a dandy of a spot... PM me if your interested.

[Boats]

So I checked Cabellas... Looks like I can either go with a Stingray or the "Cobra Marine Professional Stabilizing Plate".

The Cobra looks stainless steel looksl like it is supposed to be the better of the two.... However, it doesn't appear to have the airplane wing shape that the Stingray does.

Does anyone have any experience with these?

I kind of hate the idea of adding one to my Yamaha 150 (They look ugly), but I don't like the porposing...

Any advice would be appreciated.
Thanks in advance.
Brian

[Ak Seahawk]

I just bought the Stingray and will let you know how it works. I have the same questions that you have and am curious to see how it works.

[backlash442]

Coffee-n-rolls, this may sound like a dumb question but why would they put trim tabs on before the welding was finished as the tabs themselves require no welding.

I'd like to hear how the Stingray works as my Seahawk porpoises as well.

[fish_on]

Coffee-n-rolls, this may sound like a dumb question but why would they put trim tabs on before the welding was finished as the tabs themselves require no welding.

I'd like to hear how the Stingray works as my Seahawk porpoises as well.

I think he is referring to the tab that runs across the bottom of the boat, no the adjustable trim tabs. I could very well be wrong.

[lurking_out_loud]

I think there may be a terminology issue here. What I think was meant above is the trailing edge of the hull needs the tweek not the actual trim tab. Typically, the tail edge of the hull running surface will deform either through the heat of welding or loading on the trailer and bouncing it down the road.

What PPM does is bend the actual trailing hull edge which will either add or reduce lift to correct the porposing issues many have complained of in this forum. My boat will get its adjustment Friday since I have found that I've got a bucking bronco if I have less than a full load of fuel.

Good luck everyone. This is a fairly common issue (even with other brands!) and pretty simple fix.

-LOL

[Tacklebuster]

You can only bend that tab so much. Most of the issues from the guys I know had, nothing on that tab but a bit of magic dust could fix what they had going.

[Blue Water 23]

Sorry for the length of time to reply. I was on spring break and I stay away from the computer or any form of reading for the week.

I am not by my boat now but the part said "Whale Tail" on it. Besides that I don't know the brand but I will check. It is alluminum I believe but it could be stainless. You will not beat the $50 price on the internet I don't think. Call Portland Performance Marine, talk to Steve, and tell him that you want a whale tail or whatever Jesse got on his SeaHawk.

Bending that back tab down isn't the problem. Weighting down the bow helps but who wants to add weight to an already heavy boat. The whale tail isn't that big or goddy like you guys make it sound. You can notice it when looking at the boat and you do need to drill through the engine. However, it will help the porpoising problem, get the boat on plane faster, and increase overall performance.

My boat porpoised so bad that I couldn't trim up with the motor which created extra drag. Now it jumps on plane immedietly with the 150 and it doesn't porpoise. I also notice less bow slap when going over wakes. I can trim my motor up to increase speed and efficeincy and use my trim tabs to balance my load or put the bow down in rough water. As you can tell I swear by that thing. I think it will help any porpoising problem that you have with the old style brackets while increasing performance. Anyone that gets one and doesn't notice a difference can PM me and call me a liar, or put it on the board for everyone to see if you want. I believe that much in that stupid little part.

[Blue Water 23]

Chris

I won't be able to make it down halibut fishing until June 8th and 9th. I will be down again the end of July for halibut if quota ramins and tuna and salmon. Besides that I will be down for a few other weekends. I'll talk to you before summer so we can chase some tuna sometime.

I will post soon with the brand name of the part but I am sure that they all work the same.

I do like how the bracket doesn't drain into the bilge. One less thing to ever have to worry about off-shore.

[Ak Seahawk]

Blue Water - is there any way you could post a picture of your whale tail?

[Ak Seahawk]

I found the Whale Tail online at http://www.davisnet.com/weather/index.asp . It retails for $52.99 so not a bad deal. Looks pretty skookum to boot. I think I'll order one up tomorrow and compare it to the Stingray. Thanks for all the info!

[fish_on]

How do you think this will effect the bow angle at lower speeds like when trolling for tuna?

[Beefcake]

How do you think this will effect the bow angle at lower speeds like when trolling for tuna?
I don't see a negative - it allows you to better control the bow angle (especially if you don't have trim tabs). That is part of the reason I added it to my new boat. In the past, I have added them to underpowered boats to get better hole-shot for watersports. I have a much better power to weight ratio on this boat, but I added it for more immediate feedback to trim adjustments. At 8 knots for tuna, I'm not sure if you are trying to trim it for efficiency or to create a bigger stern wave, but I think you could do either more easily.

[Blue Water 23]

It is the Whale Tail XL on the link by AK Seahawk. It gives a picture on the link under "marine" and "products". I am not going to post a picture but that picture is the exact product.

[Blue Water 23]

I checked tuna speed first time out. The bow is still up like it was and it churns water nice still. Doesn't make a difference at 8-10 mph. I don't think there is anything that would plane you at that speed as trim tabs don't make a difference either. Good thinking though on that. I would hate to be planed trying to attract tuna.

[foxer]

Anyone try the new one made by Stingray? It apparently attaches without drilling into your cavitation plate. It costs about 120.00 though

[Ak Seahawk]

I installed the new Stingray XPII the other day and test ran it yesterday. WOW what a difference it makes. I am a true believer now! I lost about 2 MPH but I'll take it over the porpoising problem. My max speed was 42.3 MPH with no trim tabs. There is absolutely zero negative handling issues. It comes up on plane in about half the time and flat out gets it when you trim the motor up. Totally smoothed out the 2 foot chop and made the 3-4 footers bearable. I wish I would have done this sooner. Here's a couple pics of the finished product.

http://i32.photobucket.com/albums/d24/akboondocker/2007%20Boating/StingrayRearView.jpg
http://i32.photobucket.com/albums/d24/akboondocker/2007%20Boating/StingraySideView.jpg
http://i32.photobucket.com/albums/d24/akboondocker/2007%20Boating/BoatCoveCloseUp.jpg

[Blue Water 23]

I knew you guys would be happy! Like you said it only helps on all handling issues. I can't believe you lost top end though. You would think that by it not porpoising and being able to trim up more you would get more top end speed. Either way I am glad it worked for you. It looks about like the Whale Tail XL so I am sure that any brand with that same concept would work good.

[Ak Seahawk]

Thanks again for the heads up...beats going head to head with NR. I did have a 300#'er in boat with me so maybe that made a difference. 2 MPH is a fine compromise. I'm still cruising at 42 so not that big a deal. I may buy the Whales Tail just to give it a try.

Anyone out there having these same issues and don't want someone bending aluminum on your boat that's not supposed to be bent...this is an inexpensive fix that works!!!

Good luck

[backlash442]

Just a heads up. I found a thread on another site in which a mechanic said he's seen several hairline cracks form on the outdrive where the stingray was attached.

[Ak Seahawk]

Just a heads up. I found a thread on another site in which a mechanic said he's seen several hairline cracks form on the outdrive where the stingray was attached.

That's the first I've EVER heard of that happening. You gotta be more specific...what make, model, year, pics???? Maybe a link?

[backlash442]

Here you go AK Seahawk. Did you think I was making it up or something?

http://boards.trailerboats.com/cgi-bin/trailerboats/ubb/ultimatebb.cgi?ubb=get_topic;f=6;t=000601

If you do a search and read some of the threads out there there seems to be some mixed reviews. But the thread above was the first I'd heard about this issue as well. Just trying to be helpful.

[Ak Seahawk]

No, just need more info. I appreciate the lead. I didn't see anything diffinitive on the thread. They may have tightened the bolts down too hard. Could have hit something in the water, etc. You'd think if it were that much of a big deal it would be splattered all over the place. I'll keep an eye on the cav plate.

Again, I'll take all the info I can get...keep it coming.