Pad on Astro boat?

[astrofsx]

Yeah, i did tear the transom apart with 10 inches of setback, to the boats credit though, i did hit a log at speed and the transom held up for 2 years with the jackplate on it before that. I had the transom rebuilt thicker and with more braces to handle the setback. Let me know if you have any questions or anything i've tried or whetever. Let me know if you ever find a good ski prop too. While 10 inches of setback really helped out the top end, it hurt the holeshot. I havn't found a prop yet that will take off with the amount of power needed to pull a 200lb plus skier out of the water.
Steve

[RB in NM]

Yur right about the setback hurting yer holeshot. On my 18ft Fish and Ski, I had 10.5 inches total setback , a cmc hydl plate and a land and sea static set back spacer. I used a 21" Trophy for my ski prop, it'd pop a 200lb guy out easy, with 3 adults in the boat, that's with a 2.5 175 Mariner magIII. What I did for the hole shot was built a skid plate for under the jack plate, it diverts the water out of the setback on take off, other wise all the setback acts as a big water scoop, slowing holeshot dramatically.
RB

[bigboy]

Yur right about the setback hurting yer holeshot. On my 18ft Fish and Ski, I had 10.5 inches total setback , a cmc hydl plate and a land and sea static set back spacer. I used a 21" Trophy for my ski prop, it'd pop a 200lb guy out easy, with 3 adults in the boat, that's with a 2.5 175 Mariner magIII. What I did for the hole shot was built a skid plate for under the jack plate, it diverts the water out of the setback on take off, other wise all the setback acts as a big water scoop, slowing holeshot dramatically.
RB

Have you got a picture for us to show it? Will the hole shot still be hurted with the setback and skid plate or will the hollshot be the same as without setback?

[RB in NM]

I sold that boat several years ago, I do not have a picture of the skid plate on it, but I have skid plates on my two Allisons. I'll get a picture this weekend to post.

It's mainly a alumplate that attaches to the bottom of the skid plate, that keeps water from scooping into the void of the setback on take off.

Go to allisonowners.com website, on the main page, look for 'Owners info" I think is what it is called. On that page there are some pictures of skid plates some owners have built.

Lots of guys will insert inflatable kickballs into the void, that provides quite a bit of lift to the stern at rest, with the stern a little higher, hole shot improves, due to more level attitude at reat.

RB

[bigboy]

I sold that boat several years ago, I do not have a picture of the skid plate on it, but I have skid plates on my two Allisons. I'll get a picture this weekend to post.

It's mainly a alumplate that attaches to the bottom of the skid plate, that keeps water from scooping into the void of the setback on take off.

Go to allisonowners.com website, on the main page, look for 'Owners info" I think is what it is called. On that page there are some pictures of skid plates some owners have built.

Lots of guys will insert inflatable kickballs into the void, that provides quite a bit of lift to the stern at rest, with the stern a little higher, hole shot improves, due to more level attitude at reat.

RB

Damn, never thought about it. I'll take a look at that web site! I think i know what you mean with a skid plate but i'll check the site. Thx

[RB in NM]

On my XB-2003 Alli, I have 14.5 inches of setback, that creates a huge water scoop. I raced that boat in 2005 season out here. I installed 4 kickballs into the void above my skidplate. It brought up my stern almost 4 inches,, VERY light loaded hull.. cut my holeshot time in half. The skid plate works super,,,,, BUT it also makes the hull fly a bit longer when coming off power too,,, something ya need to take into consideration also.... without the plate, the setback scoops water on shutdown too, acting as a water brake.

[bigboy]

On my XB-2003 Alli, I have 14.5 inches of setback, that creates a huge water scoop. I raced that boat in 2005 season out here. I installed 4 kickballs into the void above my skidplate. It brought up my stern almost 4 inches,, VERY light loaded hull.. cut my holeshot time in half. The skid plate works super,,,,, BUT it also makes the hull fly a bit longer when coming off power too,,, something ya need to take into consideration also.... without the plate, the setback scoops water on shutdown too, acting as a water brake.

Unbelievable with those kickballs Never heard of it neither. I go with a 5,5 setback so dont think its such a big problem with the waterscoop. If you have 10" and up i can believe it makes the differnce. It also will depend in how deep your boat is floating. The higher it floats the less water scoop i guess.

[astrofsx]

I did add a skid plate and that seemed to help a little, and i tried a basketball and now i tried some foam cut to fit in there perfect. All of these helped a little, but holeshot is still not good at all. Tubers i can pull all day, but skiiers are a problem. I am currently down to a 20 pitch prop for water sports and that still isn't good enough. I am going to look for a 19 or even 18 just to do the job. Only part that sucks is that i can spin these props so easy that i can reach 6000 rpm like nothing and am still only going 49 mph with them!

[RB in NM]

Have you tried to lower the motor some ?

[astrofsx]

I have a hydraulic jackplate, so i have tried up, down, and just about everywhere. The boat takes off the fastest at about 1-2 inches from the bottom. I have thought about bending the last 1 or 2 inches of the skidplate downwards because i have seen that on some other skidplates. Right now it is just straight. Any thoughts on whether that may help?

[RB in NM]

Yes, I did not mention that on most of the ones I built, I turned down the back lip, some more than others,

[bigboy]

Yes, I did not mention that on most of the ones I built, I turned down the back lip, some more than others,

And what about a tuck in the setback. That you have more negative trim. Is this a good job to do or not?

[RB in NM]

Bigboy, If I understand ya, the tuck, you're talking about the skidplate being installed at a downward angle towards the rear, to aid in shoving the nose down on holeshot. ? ? ?
Right ?

If so, on my fishing boat, the skid plate is basically level to the pad, and in fixed position approx. 4 inches above point of the sportmaster nose.---kinda low to the centerline of the lower unit in some people's eye's, but it works very very well.... I typically run that boat 1/2" above the pad anyway..I'll get a picture posted when I find it. It's failry large, and really helps in low speed planing,and bigtime on holeshot,, no backwash during hard shutdown, (especially with the ball floatation),,,, but it sure takes a while longer to set down in the water coming off plane.Something that you have to get used to or it will get you in trouble.

The skid plate on my XB-2001 drag hull, IS angled down a bit. And you are right, it does seem to leave flatter, but there agin I do not have anything to compare it to other than the hole shot before I mounted the skid plate.

Again, I need to find pictures or esle take some more,,,,, currently both boats are setting outside the shop, all bundled up and diapered, with snow on them..... the shop is my remodeling work area right now for my home improvement project that is kicking my azzz.... RB

[bigboy]

Bigboy, If I understand ya, the tuck, you're talking about the skidplate being installed at a downward angle towards the rear, to aid in shoving the nose down on holeshot. ? ? ?
Right ?

If so, on my fishing boat, the skid plate is basically level to the pad, and in fixed position approx. 4 inches above point of the sportmaster nose.---kinda low to the centerline of the lower unit in some people's eye's, but it works very very well.... I typically run that boat 1/2" above the pad anyway..I'll get a picture posted when I find it. It's failry large, and really helps in low speed planing,and bigtime on holeshot,, no backwash during hard shutdown, (especially with the ball floatation),,,, but it sure takes a while longer to set down in the water coming off plane.Something that you have to get used to or it will get you in trouble.

The skid plate on my XB-2001 drag hull, IS angled down a bit. And you are right, it does seem to leave flatter, but there agin I do not have anything to compare it to other than the hole shot before I mounted the skid plate.

Again, I need to find pictures or esle take some more,,,,, currently both boats are setting outside the shop, all bundled up and diapered, with snow on them..... the shop is my remodeling work area right now for my home improvement project that is kicking my azzz.... RB

Nono, a tuck in the jackplate/setback so that you have to possibility to trim in a few more degrees. I think that wildman makes those setbacks. So the motor hangt more negative on the transom. This allows that the boat will plane faster so better holeshot? Some jackplates are reconvertible so you can set them up with a tuck in it. Hope you understand. I have such a jackplate it's the one from bob's that exists out 2 parts. And you can convert this so it has a tuck.

[RB in NM]

Gotcha! My drag hull jackplate has a negative 6 degree tuck built in.
It's a CMC from Allison. One of their models popular on the XR-2001 hulls. It does help.
RB