Trying an IMCO 2" shorty on my Twinstep
 

I just bought a 6hr XZ from "Sterndrivespec" with an Imco 2" shorty. It may be too tall for the already high x on my twin step but now we'll know. Unfortunately my 25' Daytona is stored for the winter so I won't know til late march or so. worst case I'll need a 1" spacer. I know the 2" shorties pickup 5-6mph on the 1.75" lower x single step. I'll fill in the results when the time comes. I also bought BC's Merc labbed 28 so that should be good for a few also. :D

Catitude,
Please post your results good or bad Ihave the same twin step hull and will very interested in your results.

Bust it out for a test run!

Yea, the weather can't be that bad, down there in Arkansas!! :D

And if you don't like that 2" shorty, you can make me a smokin deal on it ,and i'll try it on my single step 25! :cool:

You guys don't watch the weather channel, It's 30 degrees, I've got an inch of snow and I just got back from pulling wy wifes MR2 out of the ditch- Car & wife- I mean wife & car are both ok :eek:. I'm sure once all the parts actually get here it will be awfully tempting- of course there's that lack of insurance thing. :D

Update- I called Imco to ask about hooking up the speedo to the shorty (Need to use Pitot on transom) and asked about the 2" shorty for my twinstep- they sent me to Jerry May at Eliminator. I've talked to Brent and Mike before but never Jerry. Jerry is the dial in guy. He set up the twin step that did 127 in the PB shootout and has had twin step 25's up to 138 mph. Jerry told me that the 2" would work fine in the twin step and that they had tested with even higher x's. He sid it would likely slip a little out of the hole but would be faster for sure. I asked if there were any negative effects that I would be compromising- he said that it would drift more in the high speed turns (2" less rudder in the water too) instead of carving but that you get used to it, also all else being equal I'd have to slow down a little more to execute the turns (that's ok with me). He did say I might have to bump to a higher prop size but to try what I had for now. I'm very encouraged by this news from a man with this experience and credibility. :D

I have that problem at speed with it wanting to move sideways. Can the skeg be welded on and made 2" longer?

CM- I had the same thought- I'm betting it can- it would be great to get the AMS spec of the alloy- I should be able to get that from IMCO. One of my buddies is an awesome tig welder- does aerospace stuff and go-cart frames- I stick to the mig gun myself. :eek:

i had 2" shortened cases on my 27 daytona and i added 3" to the skeg. you have to weld it on with a high frq tig. any good fab or welding shop can do this and it will stay on. mine stayed on at 122 so i know it works. ;)

you should pick up speed i have done three older daytona's and they all picked up 8-10 mph the prop will blow a little as far as the speedo why not put a gps speedo in it they work so much better good luck and post the results i have two guys with 25's (twin step) daytona's wanting to do the same thing :D

Merlin- can you fax me a sketch roughly to scale and proportional- side view. Just trying to learn from what worked. 501 936 7181. Thanks :)

Cat, It should be easy to have some extra material added. I would just go to a drive repair shop if you need to. I would test it first. Or you could send it my way, we are having 70+ degrees weather here. :D

I am also very interested in your progress. We had the lavey(27 cat Hp 500EFI Whippled) out and it ran 98 on gps yesterday. I am considering the 2 imco as well. I am also debating on the imco stand off box.I think what we are planning is the stand off box (neutral) with the 2 shorty for a net raising of the x 1 inch. What gear ratio are you running ? Do you know the approx weight of your boat?

Garry,
I'm running the 1.36 ratio with a whippled 454mag. I also considered the extension box- it will change your CG which could also hurt you, I'll use spacers if the 2" proves to be too much.

Cattitude - New equipment sound great and it sounds like your going to pick up a lot of speed! Now you've got something to keep you excited while waiting for boat season.

Jerry May is a very nice guy! I've met him a Eliminator and he was the guy that put the 26"s on my boat at Havasu. Trivia point - his son is the PGA pro, Bob May - the Rockyesq guy who duked it out with Tiger Woods a couple of years ago at the PGA Championship. He's got a 30' Daytona with twin 1,100 hp engines (I believe). Watch from shore as Bob & Jerry did 140mph across the lake (water was like glass) and throwing a monster rooster. Hot Boat had a helicopter chasing them so may we will see some pictures some day.

Couldn't get my speedo to work with the shorters either -going to add a dash GPS. Any suggestions?

Hey UT, Don't you have a GPS? I don't have a speedo I just use the GPS. The Garmin 168 has a large display and you can make the seedo digits take up half of the screen, it makes the numbers about 1 1/2 inches tall. Works great and easy to retrofit.

Pyle

Thanks Cat&Mice. I have a hand held GPS, but need something to take up that space that was for the speedo and at my age, big numbers are helpful.

Catitude, It's almost time to test that thing. :D
I'm very interested in your results. Anyone know if this helps on a 25 Eagle XP? A buddy of mine bought a new one last year with 496HO and is going to put a Whipple on it if Dustin ever gets the thing built, but he is also considering a 2" shorty.
As far as my boat, I just talked to Bruce from the board yesterday, and he is sending me a whipple to get my crate moving.;)

Cat, keep us posted!

Almost test time
 

If the weather will stay 50ish or better I'll be testing around the 9th. Supposed to snow this weekend! I need to spend a little more time on the install and I'll be ready to go. Sure looks good hanging off the transom!

Uncle, I have the Nordskog indash GPS. Everything works fine with this unit. Big easy to see numbers, top speed recall, top RPM recall and compass readings all function fine. However, a friend of mine at Marine Perfofmance Products, has also installed the Gaffrig/Lovorsi GPS unit and found that one to be nicer because the wiring all plugs into the head unit . Also the sender is white instead of black like mine. Hope this helps you out.:cool: :cool: :cool:

Cat,
I am hoping to test next weekend as well. Let me know how it goes.
BC

Hotboat article?
 

John, did I see your boat in the Texoma poker run article??

Hopefully the 4" of snow melts and it warms up so I can still test next weekend.

Yes, that was me. First time in Hot Boat. My mechanic was on the first page in another Daytona 25. He actually had two pictures. :D

Hey Cattitude, whats the update on your new lower unit. You going to get that thing wet this weekend? Hows your point total with the Jeep? You going to make the finals?

delays!!
 

Does not look good for this weekend. Needed parts are not here yet, whether looks nasty (Warm but t-storms) etc. etc.

Maybe a good weekend to stay inside to finish the taxes.

Jeep wise, I'm sixth in pts in the series so far. Next event has been moved down the road to a site I am both familiar with and very competitive with my particular set-up (Rock Garden in Aztec NM).

Jeep just needs a little TLC before April events.

Shorty should be tested a week from Sunday as it looks now.:D

Shorty got wet!
 

I finally got all my parts and completed the install! Ran yesterday with 450 lbs of people, one extra battery (Normally have one) and 100 gallons of fuel (filled the tanks for the winter).

Previous best GPS with stock Bravo and 28 B1 running with just me, one battery and 15 gallons or so was 87.9, similar temps in the 60's.

Yesterday I ran 89.1 with considerable extra weight (235 lb passenger, est. 80 lb Optima battery, and 85 x 6lbs of fuel totals approx 825 lbs.) This is with the XZ/ 2 inch Imco and a merc labbed 28 Bravo.

I've got a 1/2 spacer which I will try next for a 1.5" shorty. Planing was a little tricky- started slipping at 3k, instinct was to keep it there but found it worked best if I gently moved the stick thru 4k and the bravo grabbed enough to break it over. I'm not sure if it would work this well with a full passenger load. I suspect the 1/2 or 1"spacer would be best for general recreation.

steering with the 2" shorty actually felt more balanced, a little lighter yet still controlled, did some sweeping 60mph corners and was very comfortable. With the stock Bravo it felt more "Grabby" and like it actually bit too hard at times in the corners.

After running, I did something I should have done long ago, I calibrated neutral trim and marked it on my gage. I was running considerable positive trim, I suspect too much. I find it's easy to get lulled into this as the RPM's rise but you're not actually going faster - it's even easier to get lulled when the speedo is not working.

For the cat techies reading, I put a straight edge on the bottom corner of each sponson (the rear running surface part behind the steps) and the neutral trim prop shaft is about 3/4" +/- 1/8" below the sponsons.

Overall, I'm very pleased, aside from the reliability of the XZ upgrade and the eye candy of the Imco lower, I suspect I will have picked up 3-5 mph when comparing apples to apples. I will update when the GPS proves it to me, hopefully later in the week.

Nothing sweeter than spending money making a change & it works.

I did calc. on computer & came up that if all was the same with extra weight boat should have only gone 81, for lost of 6 mph. My guess is you should with all equal, gain 8 mph. Only time will tell.

What did it do to your rpm's. I saw where you bought this prop also so what prop did you have before.

Finally fired my motor last night for a few seconds. Hope to be on water this weekend to test.

Turbo,
Unfortunately I don't have back to back comparisons with same prop. I went from a bone stock 28 to a Merc labbed 28 which I bought from Badcat at the end of last season. With this prop, and the shorty and probably too much pos. trim i was spinning 5300ish, rev limiter is set at 5450 (454 mag with Whipple). I suspect the prop is going to be real close when light and in colder temps even with proper (more neutral) trim. As you said, time will tell.

for what it's worth stock bravo and 28 Bravo one were good for about 5100 running light (1.36 grs)

I will keep posting as I learn. Liquid Cruiser and Badcat are also experimenting in a similar fashion with their twinstep 25's and I suspect there will be more data to go around soon.

How much $$$ are those Imco 2" shorty lowers??
I would like to try one on my single step 25 w/ 500 EFI!
If you in fact see an honest 5 MPH, i think it was money well spent!:D

Ron-

I think they list for a little over 3k. I got mine thru Sterndrivespec with an xz upper and all I can say is he treated me right- he's in your back yard too- central New York.

All the feed back I had was that the two inch shorty was the ticket for the single step and probably too much for the twin. I'll run a 1/2" spacer with just me and 25 gallons less fuel this weekend and post results.

Hello fellow Daytona owners, this is the Secret Agent Man. I am new to the offshoreonly site but could use a little information. I have a 2001 25' Daytona that runs 127 mph. I am interested in putting a 1" or 2" shortie drive. If anyone can help me out with information or advice it would be appreciated.

Also I am going to the Eliminator Regatta at Lake Havasu in May. My family and I are from Virginia, so this will be a long trip. I hear it's a lot of fun. Would like to hear from others who are going. Looking forward to meeting some of you online and at the Regatta.

Who's the teacher?
 

S.A.M. - sounds like you should be giving us info!:D

Is your hull twin or single step- it is relevent as the x is different and so is the center pod.

Mine's a twin, I've now got the 2" shorty with a half inch spacer installed. I have not run this set-up yet but hope to soon. The lake I live on is up 8' in the last 10 day which means all kinds of stuff floating in the middle of the lake- need a few days for the stuff to migrate to the shorelines.

will advise results.

Well, I had a 25' V-bottom that ran 103, took the information I had and applied it to this one. I could still use a few lessons. My Daytona is a single step hull, I have not run a shortie drive, my x dimension outdrive gimble is 2-1/2 inches under the bump rail which makes it very deep in the water. The key factor is making the prop lock up. I run a 34 pitch lab finish bravo, slip is 15% which is extremely high, perhaps with a little more finesse we can achieve in the mid 130 range.

If I wasn't the Secret Agent Man, I could tell you a few more things, but I can't, breaks the code.

S.A.M.- There's a guy on the board- Steve snider I think, from Indiana I believe that is in the marine biz and runs a 25' single step. Last fall I was talking with him, he had been running a 1" shorty and was about to go with a two inch shorty based on the planing characteristics etc of the 1". he would be a good person for you to speak with- he often has something for sale in the outdrive section. Have you discussed the shorties with Jerry May at Eliminator?

I'm about 1/2 way to your Havasu trip from Virginia, about 70 miles North of ft. smith/I40, In case you feel the need to stop and play.

6 more mph and climbing!
 

Update- I installed the 1/2" spacer yielding a 1.5" shorty, lost my 230 lb passenger and the extra battery, running about 80 gallons vs 100 about 10 days ago. Similar air water and wind.

94.1 GPS on the rev limiter (5400)! As a reminder 10 days ago was 89.1 all porked out and last year's best with standard Bravo prop and drive, similar conditions running me and 15 gallons was 87.9.

Now low 90's comes fast and i have to finesse that last couple digits.

The 1/2" spacer made a big difference in planing, a 1" spacer (to yield a 1" shorty would likely be best for fellow recreational guys but I suspect I'll get a decent deal on the this 1/2" one from the guy who let me borrow it.

All this from a little 454 mag with a whipple! I'm probably done tweaking for now, will keep my eyes out for a deal on a labbed 30.

Cattitude – Congratulations! Couple of questions. First, with the 1 ½” shorty, where is your prop shaft in relation to the bottom of the boat. I read above where you said it is ¾” below the sponsons, but yours is a single and therefore in the middle. You must be talking about the center pod? T2x and Philip have been convincing me that my prop shafts should be 1 ½” above the bottom of the boat. Tried to measure that, but its tricky with the steps. Going to try and catch Jerry May at the lake and have him take a look at it. Second, didn’t you say you’re on the rev limiter with the new labbed 28”? If so, it wouldn’t help going to the labbed 30”, would it? Or do you have extra throttle at the rev limiter?

Bottom line, that’s real kewl! Worried that those last 6mph are going to haunt you. Maybe switching to the 1.50 gear?

Whoops!
 

UT- could be you're a little dislexic (Could not even find that one in the dictionary) this morning:D 1.50 gears and smaller props would slow the boat down if I'm on the rev limiter now. the 30 lab would likely pull r's down 200 or so and squeek out a couple MPH- a cool weather prop as the 28 will likely be a good hot weather prop.

I'm tickled to have a solid 90 MPH boat, especially given the tame reliable nature of my setup. I'd rather be slower and reliable than the fastest and getting towed in.

The prop shaft height I spoke of earlier is relative to the bottom running edge of the outer sponsons, with the 1/2" spacer it would now be 1.25" below. I uses a relatively scientific method, used two long straight edges and a visual plane- it's as close as you can get without a CMM or Jig.

Keep in mind the worthy advice you're getting is for twins and I suspect the majority of their experinece is on longer east coast cat hulls. every boat is different- especially single vs twin.

Cattitude – I’m certainly not dislexic (or dyslexic), although I definitely have trouble reading at times.:D

Mark at BAM made a case that 1.36 gears are “too much” for my boat and I should be running 1.50. The explanation was to far over my rookie head. However, actual testing has proven Mark to be the winner on prop advice for my boat – over the likes of Bob Leach and Jerry May. Thought you might have better luck understanding his explanation.

On the prop shaft depth – I am totally confuse. Next time at Eliminator I’ll check out a twin step 25’ so I know what I am talking about.

Hey Uncle Toys, to determine your X-dimension, 1st you must level your boat, then level your drive, take a small piece of string and tape it to the back of the bottom of the sponsons. Take a square and measure the center of the prop shaft to the string, that will give you a good idea of your height of your x-dimension.

I've talked to Jerry May and I cannot get good solid information from him on optimal drive height. Do you think it's because I'm on the East Coast instead of the West Coast?

Changing your gears to a 1:50 and running a 30 pitch prop will increase your mid-range and maybe gain a few mph on top. I have experienced 454's lose mph with 1:36 gears, requiring more torque to turn them. Yes, in general, 1:36 gears require more torque, 1:50 gears may be suited for you.

Does your engine have a hydraulic cam? If so, perhaps you can wring it out to 6,000 rpm. More rpm equates to more speed. Don't be afraid to let the motor wind out.

Here is a formula for you to use to see what your prop slippage is as oppose to mph.
RPM X Pitch divided by Gear Ratio divided by 1056 = theoretical speed minus that by percentage and you will see what your % of slippage is.

I have a 25 Daytona, single step hull, a blown 540 running 127 mph. Looking to install a 1" or 2" shorter drive. Are you going to the Havasu Regatta?

S.A.M.

S.A.M. – Glad you brought up the Regatta, I had forgotten about it. Going to discuss it tonight with my wife and daughter. I’m sure it would be a slam dunk except its Mothers Day weekend, so…..

I can’t imagine Jerry May would treat you differently because you’re on the right coast – he’s definitely not that kind of person. Actually, I haven’t notice an attitude from the left coast towards the right coast at all. Might try calling John Behman (sp?) at Eliminator. He is Jerry’s rigging partner (most of the time).

Torque could be the difference Mark at BAM was talking about considering my boys are still natural breathers. So Cattitude, maybe it doesn’t apply to you considering your enhance lung capacity.

Your method of measuring the prop shaft depth sounds like the best I have heard so far. But one question, how do you level your boat? What do you use for the reference?