Re: Engine Shop
 

80 hours of trouble free boating with that kind of power is great. If the internals are showing some wear that need to be addressed what upgrades if any do you plan on making to the drive?
Rob

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I already have an Imco SC lower and XR upper. I have all good parts inside it, so there is not much else that can be done. I got the boat home today, pulled apart the lower. The gears are in pretty good shape but can use replacement for next season. Here is the link from tech q and a

http://www.offshoreonly.com/forums/s...d.php?t=142829

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Rob, you are running speeds now where cable steering just isn't safe. No steering system is going to eliminate the loosness of that hull at the top end. You made the right call. :cool:

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Thanks Jeff, I am trying to justify the expense. The best I have come up with so far is less money to spend on the next power upgrade.

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I picked up the boat today and took a few pictures. I wanted to share some of the changes recently made with the rest of the Checkmate owners.

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Looks great! Congrats!

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Thanks Magic. I feel like we are slowly transforming the Checkmate into a legitimate performance boat.

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Checkmates have alot of potential for speed. There are many boats that run in the eighties with big power.

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Rob,

Looks great.

Vinny

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Thanks Vinny

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Are you thinking about supercharging? I have seen a few used procharger set ups for sale lately. Unfortunately, many of them were for carb set ups.

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I am not sure what we will do. We may stay with our current short block, rebuild and supercharge. The other option would be to start fresh with a larger displacement NA motor. The good news is we have several years to think about it. :D

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I would like to see my boat run faster, but I would rather have a bigger boat. I guess I will keep mine the way it is until I move up. You know you can never have too big of a boat for Lake Michigan.

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A smaller boat is easier on the retirement fund and takes more driver skill in rough water. :evilb:

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I hear ya, but NOTHING BEATS A CIGARETTE! :evilb:

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Here are a few more pictures of the Checkmate. The boat behind the Checkmate is currently one of the faster boats on our lake.

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It is that time of year to start looking at your trailer and maybe even pull out last year's boating magazines because you have memorized all of this year's. Well here is some food for thought on slip percentages found in the September 2005 Powerboat Magazine under the 525EFI Dogfight article. Eliminator 27 Daytona 81.8mph@5200rpm=80.4mph theoretical speed :eek: , Hallet 255 Open Bow 75.3mph@5000rpm=77.3mph theoretical speed or 2.6% slip, Laser 25 Fury 77.1mph@5200rpm=80.4mph theoretical speed or 4.1% slip and Shockwave 25 Tremor 79.8mph@5300rpm=82mph theoretical speed or 2.7% slip. The above four boats ran 525EFIs with Bravo XR drives with 1.5:1 gear ratios with Mercury Bravo One 15 1/4" x 26" props. Any ideas on what's going on? Go Bears :drink:

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Yeah, magazines lie like hell!! How can they claim to be on the positive side of slip???

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I agree magazines to have keep there readers and advertisers happy. I am sure at times that is a delicate balance. The Eliminator 27 Daytona is a very efficient single engine IO hull but all of the boats they tested for that article were flying. I wonder if they were running the boats in salt water. How much speed will your boat gain by running at sea level in salt water vs. 1000ft elevation in fresh water? How much less slip should you expect on the same boat running in salt water vs. freshwater?

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While I have never had the opportunity to test in fresh water, I have not heard of any measurable difference in performance between fresh and salt water. Altitude is another story. As anyone would expect, the loss of horsepower attributed to altitude only increases the higher you go. I am sure that it exists, I dont know of any actual formulas that can measure the loss at specific altitudes.

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I was under the impression salt water is more buoyant and and easier to lift the boat out of the water(less drag). I am sure the racing crowd (those who participate in salt water and fresh water events) can confirm or correct this statement. Vinny your boat was running a good 2-3mph faster than our's with the 454MAG, maybe that is just driver skill. :mad:

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Rob,

I absolutely agree with the statement of salt water being more bouyant. There is no questioning that. My thoughts and let me reiterate, thoughts, no testing or scientific experiments to back me up, are that when our boats are up to full speed, there is just not enough hull in the water to take advantage of the salts bouyancy. Thereby, the advantage is negligable at best. I dont have an answer for why my boat was a few mph faster than yours with the same power. I am sure you know how to get to maximum performance just fine.
I can say this for sure... I used to be heavy into slolam skiing. I have skiied in salt and fresh water. I noticed that when floating in the water waiting to get pulled up, I was a bit deeper in fresh than salt water. That made pulling up more difficult.

Vinny

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Vinny,
What size Dana tabs do you have? Did you install them yourself? If so, how difficult was that project? Thanks in advance for any insight.

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Rob,

I have HP-1000 tabs. The problem with installing these tabs is the extra holes you will have from the original tabs. I am not skilled at fiberglass repair. What I did to repair the old holes was hammer in wooden dowels drenched in white marine tex. Then a quick coat of white gel to finish it off. Unfortunetly, the repair looked like $hit. So, I covered some of the mess with a gunnel step plate. I'll take a picture later and post it.
The next problem would be the indicators. There is just no easy place to mount it. I'll post a picture later as well. It is the best I could figure mounting it.

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OK, just came in from the garage. I took a few shots...

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Vinny,
Thanks for the pictures. Did your nose cone add any speed? Did you modify the X-dimension?

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The lower is a standard length Imco SC. I put the drive on when I upgraded power, so I dont know if the bulleted lower did any good. I have never tested a standard XR lower. I have tried a -2 Imco shorty. I didnt have enough time to fully test with it. I did gain some top end speed but felt that the handling and ability to get on plane were too badly compromised to make the investment worth while.
Unless I can get a deal on a good used -2 Imco lower or better yet a good used case, I am not going to bother. I figure I can always throw a spacer in and be back where I am now.

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Vinny,
Did you mount the Dana tabs in the same veritcal position as the Insta-Trim tabs on the transom? Do your Dana tabs exceed the length of your swim platform? The Dana tabs look great.

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Rob,

The Dana tabs are mounted in the same location as the original Insta-Trims. They measure 24" long and dont go out past the swim platform. It's close, but not past the end. When down, the swim ladder clears them as well. Actually, I use then as a step to get back in the boat when in the water.

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Rob, if you go with Dana tabs or K-planes, I would mount them the same as your existing tabs and follow the deadrise of the hull. If you are serious about adding bigger tabs and would be interested in going with a set of 280 K-planes, let me know. I have a source you can possible go with to get them at a significantly reduced cost.

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Jeff,
I appreciate the advice and offer. I think at this point I am just window shopping. Although the boat would run better in rough water with good tabs.

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Nice ride ! I have a 251 as well. I have played with several combo's. Currently I have a Mod 468 and run just under 80mph. I bought a bunch of stuff to upgrade to get over 80 but have not gotten to try much out, as I havent used the boat much last year. I am considering selling every thing boat and all. I have an Imco 2" shorty, 12 " Imco box, Big tabs and assorted stuff, maybe you would be interested?

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I would be interested in the Imco -2 shorty lower. All I reaaly care about is the case.

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I may have an interest in the big tabs. What kind are they? Do you have indicators?

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I am ready for big tabs too. Am thinking the kit from Trick. Look similar to the Dana tabs, are they the same ??

Anyone tried modifying the stock electronic sensor to use on aftermarket rams for indicators ? I will be replacing Insta-Trim dual ram system.

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I thought about doing the same thing. I couldnt find a good way to do it. Besides, the stock LED guage I had sucked. I couldnt see the LED in the sunlight.
It may be a bit more work, but putting in mechanical indicators is the way to go.

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The electronic one's use the piston running in the plastic cylinder to indicate position, not sure if you could adapt them to read with the aluminum rams. Any way... I bought the lower as a package, ext box and drive (bravo with imco lower) it is complete. The tabs are from Fred at Trick, brand new with Pumps I bought them to use with the Box. They are Red, I can take photos if your interested.

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What brand are the tabs? Do you have indicators? Pictures would be appreciated.

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Vinny,
I just checked out the HP 1000 tabs kit on Dana marine's website. Other than the Gaffrig indicator gauge what other parts did you have to buy to complete the set? The price seems reasonable for the tabs, pumps and switch.

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Rob,

The kit is complete. Everything you will need is included. You just need the complete indicator kit... guage, cables and thru-hull fittings.

Vinny