Changed Drive Shaft ????????

[Peterjfinch]

Yep, sat right on it. I would have thought, even with a jack plate, it will still have to go down, for the skiing hole shot. Don't think a 6" plate will allow clearence for the steering.

[Burty]

if you are running sea star then afraid not

below is a P21 with standard box on 20" shaft

[Peterjfinch]

That picture looks like the cut down is a bit lower than mine, do you agree? Is there nobody who knows what the correct transom should be, for the standard 21.

Peter

[Burty]

I agree that its cut down more than yours. JF may well know the height of the transom

[Peterjfinch]

I can see the skill saw comming out soon. What should the correct possition be, for the center of the prop shaft, to the bottom of the pad?

[JamesM]

Looking at the photo's I would say that niether your's nor sinkunits transoms have been cut. The 21 does have what looks like a cut out as standard.

From the video it looks like your prop shaft is approximatly 3 inches below which, cooling issues (with a standard gearcase) aside, is a good height to run at. Once you've got your nose cone and your happy the cooling problem is solved try some different props as this could be the cause of the porpoising. Also you mentioned that your fuel tank runs the length of the floor, is it correctly baffled? A 21 pitch prop is to small for that motor on that engine if you want to go more than high 50's anyway. With the right prop I would say you will see high 60's. Whoever told you 70 to 75 was being a bit optimistic I reckon.

[Peterjfinch]

Johnny,

Tell me more. I agree that Sinkunits transom looks very similar to mine. What prop do you suggest, considering the general attitude that there's not enough bow lift? I would be happy with the figures you quote, I'm not racing. First things first, in my opinion, is to protect the cooling system, with the cone / low water pickup. What do you think. What about set back, for bow lift?

Peter

[JamesM]

Originally Posted by Peterjfinch

That picture looks like the cut down is a bit lower than mine, do you agree? Is there nobody who knows what the correct transom should be, for the standard 21.

Peter

Its possible that the blue 21 in the photo has had the transom cut down. Alot of the 20's that I've seen (probably more than not) have had a couple of inches cut out of the transom. I suspect this was to get the motor lower as lots of people seem to think that the correct height is with the cav plate level with the bottom of the V. Before anyone says it, I very doubt that all those P20's ran a short shaft at some point.

If the transom height is the same as the 20, and I suspect it is, Ross Pupiesballs Mutz Nutz will know what it is, He's probably taken more transom measurements on the 20 than SB.

[JamesM]

Whats up the front of your boat?

[Peterjfinch]

Nothing beyond the dash. I did add two layers of heavy glass / epoxy resin, to the underside of the bow, as I noticed some creaking when body weight was on it. I could see some prat stepping off the key, onto the bow and cracking it. Apart from that, there is the original bow tank, without any fittings. I don't know about fuel tank baffles, I did have the re fill point moved, from between the front seat base's, to under the dash.

Peter

[steve hutch]

sinkunit transom was cut,originally had 260 20 inch,then 300 drag 15 inch

[Peterjfinch]

Hi All,

Just found a picture of the tank. I was told it was the original style?????

Peter

[sinkunit0]

15" drag on mine

[Peterjfinch]

Hi, that looks like the prop shaft is above the pad, but I guess the extra set back, from the 15" mid, compensates for that. Your transom looks the same as mine, could you measure it, against the transom, mount to bottom? When the cone arrives I'll try her again but am sure I need to find a prop to try, it's diffecult over here. I'll keep you informed.

Peter

[Peterjfinch]

Can anyone advise about the jack plate I will need for this. What would be the best size? Am I right to think, that larger set back is not so good for sea use? Any more ideas on what prop to use?

Peter

[sinkunit0]

go for 6" setback

[scottyboy]

The reason your not coming "un stuck" until trimmed out alot is because of the belly tank! I had this prob with my racedeck p21! I fitted a six inch setback to increase bow lift but it still took alot of trim to get it "un stuck". Also had the standard bow tank but never used to use it! Mine also only used to lean over if trimmed in to far! If you are going to run your engine higher,on the surface and on a lifter (Lifter not recommended) i found that a larger diameter (14.25"dia 23"pitch tempest) prop was faster but apart from that i used to run a Worked lazer 2 22" prop (bought off burty) and i think the best i ever saw was 66mph?
Move ya tank to the back and see what happens. Oh and i was running a 20" shaft with the point of the box level with the bottom of the boat with jack down.

[Peterjfinch]

Hi Scotty, I was confused, now, *!/?????****!!!!. It will be diffecult to move the tank, I've renewed the entire floor, over it. This includes sides and seat dox supports. It would destroy a lot of work to do that. Is there another way? I don't get the leaning now, not at all. It's running level and quite stable. You say a lifter is not recommended, please explain. I've been led to believe that the extra setback helps to lift the bow. Maybe a further setback would work? I was only thinking of a jack plate, so that I could lower the engine when skiing and casual. My point is about 3" below the pad now, with a 20". If I were to cut the transom down a bit, giving good hole shot, then add the lifter, to bring the engine back up for speed and give setback. Would a good bow lifting prop give me the top end? Do you suggest the 14.25"dia 23"pitch tempest prop for this setup, using my existing laser II for sskiing? Mid 60's would be fine for me, it's only for pleasure. I just want to get the best from her, after all the work.

Peter

[scottyboy]

Hmm? i may made my floor so it was removable to gain access to the tank (what if you had a leak).If you cant get it out then i know its not the best thing to do but i would leave it under the floor but not use it and have a tank made for the rear and use that! The best thing you can do is shoot "old beardy" a pm he will tell you everything you need to know about setting up a P21! If anyone can set up and drive a p21 its him!

[Peterjfinch]

Thanks again, I'll PM him now. If you speak with him, please let him know.

Cheers

Peter