Taking a dive

[MJ13]

Can someone please help me understand what is happening, or offer any tuning suggestions on how to get my stock impulse to stop submarining or taking a hard nose down dive into the water? This has happen to me twice in two weeks, once on 5S, and once on 4s, costing me an unretrievable hatch cover and seal each time. On the most recent occuracne, it nearly cost me the entire boat. The first time, the boat ended up right side up, and I was able to drive it back to shore, but with the most recent occur acne, the boat ended up upside down.

Why is this happening, and what can be done to prevent it from happening again?

[MJ13]

Does anyone have anything to offer? Is more information needed? Am I missing something?

[tlandauer]

Typically when such a question is asked on a boat that has been released for a while and there are a good number of threads on the subject, the "priority" goes lower on the 'agenda' , this may explain why you have not received specific replies pertaining to your questions.
I don't have this boat and therefore i would not be a good candidate to answer anything i don't have first hand experience about.
One thing did pop into my mind as you have mentioned that you lost two hatches, while I am not familiar with the Impulse, is there a way to tape the hatch down? Taping the hatch is mandatory unless you have custom cowl locks installed like Kfxguy here.
What prop are you using? Incorrect selection of a prop will give you a host of problems such as barrel role and chine walking but you did not mention that info.
How is your COG? Is your trim tab level with the bottom? To start, they should be level and your strut should be in a neutral attitude, neither positive nor negative.
If I am correct, the IM has a wet Tube which allows vertical adjustment as well, try to raise the strut up while maintaining a neutral attitude ( prop thrust angle that is).
Does your boat nose dive on straight or during turns?
Tuck the rudder in if you can , looking from the side your rudder's bottom leading edge should be closer to the transom, this will help during a turn.
Assuming that your COG is correct, next you should set the prop thrust angle "positive", the blades should point up that is----very little .
The stock trim tabs are a bit difficult to adjust uniformaly , IMO because they are not adjusted with a screw, you need to bend them carefully. Use the edge of a ruler and place it across the bottom of the boat and the trim tab to see how it is adjusted. This will afford you the opportunity to see how it is adjusted quickly and somewhat accurately.

[MJ13]

Thank you for replying.

I did use Dynamite marine tape to tape down the canopy. In both instances. the canopy was violently thrown off as the boat submerged in the water. The canopy and hull also have a lock mechanism built in, however, I taped it down to be extra sure it wouldn't fall off. Didn't seem to be enough though. As far as the prop, I am still using the stock prop, which supposedly is a 1.6 in x 2.5 in stainless steel prop. I have an Octura X445 that has been sharpened and balanced waiting to be tried. I am a little wary of trying it though, as it seemed that the dives were both caused by hitting a high rate of speed. The COG is approximately 2/3 of the way to the transom, should I attempt to relocate it? Using the ruler method, the trim tabs are parallel and about 1/16" above the bottom of the hull. The strut currently has a very slight negative trim. I set it that way, as the boat seemed to be extremely loose --hoppy, bouncy, and chine walking-- with neutral trim. When the first dive occurred, I had thought that the boat might have possibly become too loose. The first dive happened with neutral trim. In hindsight, negative trim might have not been the right adjustment to make given the outcome. I really know very little about boat trimming.

Both nose dives occurred just as the boat hit maximum speed on a straight. The boat became loose, then it was kind of like the transom was thrown up, while the bow pushed down hard, and under she went.

[tlandauer]

Trim tabs sounds like in good place. My only experience with somthing like this was in a DF 26 where I had a monster motor and it will dive. I changed to a smaller and slower motor and it never happened. In your case since everything is stock, I think you need to further fine tune your boat. COG should be 30% from transom and yours is not far from the target.
If you look at the last part of your bottom, 1/3 from the transom, are there any "hooks" in the fiber glass surface? You need to look at it in the correct angle against the light. A "hook" is defined as a dimple or a bunch of dimples on the surface. The "hook" will stuff the bow in no time. The bumps are called "rocker" and as the name implies, that will rock the boat constantly. The riding pad area of any boat, in this case the triangle area in a mono should be free of defects like this. I had to do a ride pad on my Insane 34 mono, the difference between before-and-after was astounding.

https://forums.offshoreelectrics.com/...insane+34+mono

I use every day electrical vinyl tape and I run my fingers to press on top of the strip several times to make sure it is taped down, I am not familiar with Dynamite tape, but US Made electrical tape is very good, I even go to an electrical supply store to buy different colored ones to match my hull color. I have had many flips and because i have a front retaining tongue on most of my lids, so far , knock on wood, so good.
I actually find that Hockey Tape NOT AS GOOD, its adhesive is not as pliable and if there is an air bubble, water finds its way in and it will undo the taping. Of course this will invite a debate.

[MJ13]

Wow, that insane 34 looks way smoother than how my impulse is currently running. If you have seen those "overdone" promotional action videos with the Impulse running really loose, that is how my Impulse has been running.

Interesting note about the electrical tape, I will have to try it. Good color match --black/black, and a lot more affordable than this specialized hatch tape stuff.

I looked at the bottom of the hull, and there is definitely a depression in the pad area on one side. It's a fairly large depression too. Is sanding, filling with automotive fiberglass filler, and repainting the preferred method of correction?

[tlandauer]

Wow, that insane 34 looks way smoother than how my impulse is currently running. If you have seen those "overdone" promotional action videos with the Impulse running really loose, that is how my Impulse has been running.

Interesting note about the electrical tape, I will have to try it. Good color match --black/black, and a lot more affordable than this specialized hatch tape stuff.

I looked at the bottom of the hull, and there is definitely a depression in the pad area on one side. It's a fairly large depression too. Is sanding, filling with automotive fiberglass filler, and repainting the preferred method of correction?

Yes, but before you start , there is a tutorial you should read and watch:https://forums.offshoreelectrics.com/...nting-Tutorial , now this is for the MG but I believe you will learn something and apply to your boat.
It is unfortunate that you hull has the depression, I have not heard that this is a common problem on the Impulse but production variance and sometimes temperature during transit and how the hull is packed in the box can do a number on the fiber glass body work.
DSCN4932_5181.jpg DSCN4933_5182.jpg DSCN4936_5185.jpg this is how smooth after fine grit sanding: DSCN4968_5212.jpg
I basically could not drive the boat the first time in water, it will barrel role and do all kinds of crazy things. I was reluctant to do this procedure since i have never done it before. I had more bumps than depression and so I had to sand quite a bit. My concern was not to thin out the hull too much in doing so. Luckily there was a second layer of FG inlay inside the hull and it was pretty thick and strong. The area where I filled most was actually not a depression but a "build-up" so I don't have to sand too much. It was tricky but to my amazement the end result was a huge improvement. https://forums.offshoreelectrics.com/...pend-a-morning
Third one down the link is another run of the Insane, this time it was a metal prop, I believe on her maiden I forgot to bring a metal prop.

[MJ13]

Definitely a smooth boat. The tutorial makes perfect sense, and I will be doing the hull blueprinting over the next few days.

[duty]

Definitely a smooth boat. The tutorial makes perfect sense, and I will be doing the hull blueprinting over the next few days.

so im curious how you made out and what you found out ?

[MJ13]

While I had completed the work a while ago, today was the first time I had an opportunity to get the boat back onto the lake. Life has just kept me way too busy.
The results: A 110% improvement. The boat was stable, no longer hopped along --well except for hitting some waves, and ran fast and smooth.
The process I used: I mostly followed the tutorial. To check flatness, I sprayed a coat of VHT white epoxy paint as a base, then a thin even coat of VHT epoxy black on top of it. I let it fully cure, and sanded away enough of the black, to reveal any further depressions as etching in the white. I had to do that a few times to get it as near perfect as possible. When there were no black etch marks left in the white. I then sprayed a few more coats of the black.

[tlandauer]

While I had completed the work a while ago, today was the first time I had an opportunity to get the boat back onto the lake. Life has just kept me way too busy.
The results: A 110% improvement. The boat was stable, no longer hopped along --well except for hitting some waves, and ran fast and smooth.
The process I used: I mostly followed the tutorial. To check flatness, I sprayed a coat of VHT white epoxy paint as a base, then a thin even coat of VHT epoxy black on top of it. I let it fully cure, and sanded away enough of the black, to reveal any further depressions as etching in the white. I had to do that a few times to get it as near perfect as possible. When there were no black etch marks left in the white. I then sprayed a few more coats of the black.