Swim deck experiment

[Surfdad]

I have an older Tige - an '02 23V, with the huge swim deck that has the ears up towards the transom. I've never bothered to trim the swim deck down, it always seemed like it was the LOWEST of the LOW priorities. The past weekend, I had some free time and so decided test a different size, using plywood - ala RagBoy's efforts. I cut the swim step down to just the barest minimum, which was basically the outline of the frame.

I have some video from a rider looking down at the transom and will eventually post it in this wakesurf aricle.

Here are some stills of the two different decks - the orginal and my plywood mimimalist shape underneath.

[Surfdad]

So I'm sure we've all heard that pulling the swim deck out of the water will improve the wake face - not the case with my boat! The darkside wake developed a huge frothy lip, as well as, became much shorter and steeper with the revised swim deck. The steepness added about 4 to 6 inches in the height of the wake also.

It's a little hard to see, but you see some froth along the spine at the lip.

[Surfdad]

I think the collective thinking is that removing the swimdeck from the water helps but in my situation, it exacerbated the issues on the darkside and overall increased steepness and height, while also shortening the pocket. Can you see where this is going? My swimdeck was acting as a sort of trim tab. By extending into the wake, it was pushing the bow down, altought not terribly efficently. What it begs to ponder, though, is if that swimstep is acting in some capacity as a wake shaping device, what could be added underneath it that would be benefical for smoothing or changing the shape of the transition?

The regular side face cleaned up but way steeper.

[somebodyelse5]

interesting.
I know that on my boat, on the port side the swimdeck hits the water and really messes up the lip. Basically flattens the barrel and grabs your back foot.


Lets look into why the darkside, is the darkside. Simply because the propeller spins the way it does?
If the swimdeck is directing the flow of the water to achieve a better wave, acting as an in-efficient lever, the prop wash should have no effect and the waves, port or starboard, should be symmetrical, right?

So the swim deck must have some relationship with the propwash, or the water the prop is expelling that is not directly behind the boat. Or something to do with rotational torque exerted by the drive train? Just a few thoughts. Miniscule these forces may be, but seem to be making a big difference.

So if mastercraft took the twin screw X80, made the props as close together as they could and spun the props in different directions ( port side LH and starboard RH....i think thats right?) you could potentially have the ultimate darkside wave. I think a scaled down X80 could be the ultimate surfer, like a twin screw X25 or X2.
Surf package allowing you to pick which motor you run depending on the surf side. And maybe some channels under the boat directing the prop wash. Could utilize gates to allow port/starboard preferences. gates would be easy, could be like the gate on the back of the nautiques.

Just some ideas I have floating around. I am aspiring to become a marine engineer, working to get my Mechanical Engineering degree first.

[Surfdad]

I am NO hydrodynamics expert, but with my Tige, which has the spray pockets, there is an effect by the convergence of the various streams of water - prop, both sides as they funnel back and in towards the center, but also from the inside vertical surface of the spray pockets. Interestingly enough, less impact from the swimdeck dragging through the water. I think with my setup, the corner hitting the water, sweeps up and on to the spine so it's mitigated.

I wish I knew more about how it actually impacted the wake so that I could "manage" it to my advantage.

[somebodyelse5]

Yea, its one of those situations where it would be simple to find out, but the tools and knowledge you need arent readily available haha. One day Ill set up a full scale test for ya, k?!

When I have enough weight, the nasty channel seems to go away. Last time the boat was really loaded down, i dont remember it being there. Its almost as if the swim deck needs to be completely underwater or completely out. if its just dragging it just causes problems.

My new ballast should come tomorrow, got 2 fly high jumbo V drive sacs will be switching the 400# (i think thats what they were) on each side with a 1100# on each side

[jdj06c]

Surfdad, Do you think the spray pockets negatively effect the surf wake? I have them on my 21V. I know some guys have filled them in and they say it has cleaned up their wake but I believe that was their wakeboard wake, not sure how it would effect the surf wake???

[somebodyelse5]

spray pockets?

[jdj06c]

Tige had cut outs at the back of the boat on older models which are referred to as spray pockets.

Here are two old forums about owners doing mods and filling in the pockets

http://www.tigeowners.com/forum/show...=spray+pockets

http://www.tigeowners.com/forum/show...=spray+pockets

[bobbysky]

I filled in my spray pockets, and it tremendously helped my wakeboard wake. But I'm not a good enough surfer to see if it helped on the surf wake. It seems much better this year but I also have 850's in each compartment instead of the two 400's stacked on each other. I also put a fat brick (150lbs) and a 300 on the surf side. No weight in the bow. And all the peeps on the surf side. And it seems really good.

[jdj06c]

bobbysky, that was a nice job too on your boat! Not sure if its worth it to do it for me. We spend most of our time surfing.

Do you have any before and after shots of the wake? If not, post a pic of your post mod wakes (wakeboard and surf) if you have them.

Thanks!

[somebodyelse5]

Wow, seems like a lot of work. My boat doesnt have em.

[ragboy]

On my boat also, with the deck OFF, I got a rooster tail, and that froth, so it was NOT better without. I found there is a size that is required, if you go too small it gets worse. The key on mine I think, is just the smooth bottom. I have some video somewhere of the wake with and without the deck.

[Surfdad]

Hey Robert - what are the dimensions of your final deck?

[ragboy]

Don't remember, out of town. I will be back later this week, and will post dimensions by Friday.