Checkmate Predictor Engine Choices vs Top Speed for New Project

[Check_Jo3]

I have been searching far and wide on this site and the Checkmate forums and what I have gathered on these Predictors is (approximate speeds)

150 hp (2.0) = ~ 68-74 mph
175 hp (2.5) = ??? mph
200 hp (2.4, 2.5) = ~ 78-83 mph
225 hp = ~ 90+ mph

I am thinking that a 175 black max should do 75 fairly easily and be a nice compromise between the 150 and the 200. I have read that getting up toward 80 can cause prop to wash out and jack-knife the boat without a nose cone. I am picking up a Predictor this week and am toying around with which engine to go with. Not sure on props but the plan for the setup is to go with hyd steering, bobs 6" hyd jack plate, hot foot.

The goal here is to go faster than my old mans 21 starflight :D its got a 2004 250 yami on it and has been 72 with no real setup time. It's kind of a death trap at this point tho as it needs a transom and stringers not to mention he's been running the same single cable steering since he got it (yikes) :nonod:.

Common sense is telling me I should shoot for 70-75 with a 150 hp or 175 hp but the voice in the back of my head is saying to wait for a nice 200 hp 2.5 to come up and let it eat. Any thoughts? I am planning on starting a restoration thread once I really get going on it. Thanks to everyone on this site as I have learned a lot reading over the years

[largecar91]

I personally would try to wait on a 2.5 200(or even a 2.4 200) . You are looking at around the same weight for the Merc v6's so you might as well get the most HP you can right off the bat. Rig it right with the things you are planning. Make sure steering has no play. Solid mounts always helps. Learn to drive it. You should run 80 no problem and smoke your dad!

[Pulse186]

2nd vote for the 200 2.5, most hp for the same weight.

Love the 2003 on my checkmate, has an electronic oil pump and supports smart craft, also records hours which is nice information to have.

[TooStroked]

I had a 1989 Checkmate Spectra 201 with a 225 Yamaha on it and the best it would run was 72 MPH - and that was with a ton of positive trim. Checkmates are great boats, but slapping a 200 on a transom designed for a 125 - especially on an older boat with questionable stringers and transom - is asking a bit much.

The thing you might want to keep in mind is that the Predictor is a 16.5' boat rated for 125 HP. Sure, most of us have disregarded the manufacturer's ratings, but you will run into trouble if your insurance company finds out - especially if you crash.

[Dave S]

Ck mates are Welt built........So they hold up longer thue the years..........Weldt..... rich in rasiun........:cheers: No air bs........JMO.........

[altamate]

Make sure the transom is good, then 10 -12” or more of setback on a hydraulic jackplate with the prop shaft centreline at 1.5-2” above the pad at the top of the travel, that way the chine walk is more manageable and you can get to those 80+ mph blasts that the 200 can push it to. You will need a low water pickup and a water pressure gauge as well.

[AlliStan]

Another vote for a 2.5/200. Mine was built by Wisenecker several years ago and was estimated to be at about 240, with a Mercury ECU and horn. It's strong on my XTB. I've run it 87 mph and had pedal left. I really think it's a 90+ setup. Running a Sportmaster and a 4 blade Hoss 28", and sometimes a 3 blade big ear 28" chopper. Fourteen inches of setback. Outback Outboards is building me a 260 right now, with Chatfield rods and CRT pistons . It should be a lot stronger with it up top.

Two point fives, forever!

[Check_Jo3]

Thanks for all the replies!
Would that 10"-12" of setback be too much? I was originally thinking a 6" hyd jack and run somewhere around even with the pad with some sort of 3 blade. Some say that a 4 blade will lift the stern more than this hull would need. Most I have seen recommended on these is an 8" jackplate. I would think that if there is too much setback then it would lead to porpoising issues no?

Just for fun here's my dad's boat on my truck!
500572

[David]

We ran a 115 HO Etec on a 16’ Baja with 4” of setback and that was more then it needed

[TooStroked]

Although I will agree that Checkmates in general need a lot of setback to gain enough leverage to carry the bow, be careful. My Spectra 201 came with a sticker on the transom stating that Checkmate would not warranty the hull with a jack plate on it. (Yes, true story.) I went ahead and tried several different plates with up to 10" of setback. More speed, yes. Then I cracked both transom knees. After repairing and beefing them up substantially, life was better. Still needed more trim and more setback.

[bbezok]

Had an Enticer I bought new in 1985 (open bow version of Predictor), 85 Merc 150 V6, Land & Sea jack plate, 26 Chopper.....would run 72-73 once you got past the Chine walk....was a fun boat.
Just take your time and learn how it acts before you ring it out, 80 shouldn't be out of reach.

[Check_Jo3]

bbezok.. did yours have any porpoising issues while going at slower cruise speeds?

[bbezok]

Not at all, it was mostly used for skiing and tubing so at moderate speeds tracked very nice, but remember open bow has a heavier nose so that might have been why. With a 21 pitch prop she would almost take your arms out of socket on a deep water slalom start.....

[David]

Our 115 Etec was a 390 lb motor, nearly the weight of an old V6 Merc. It did poor porpoise at 20-25 with 4 in the boat. I can’t see needing much setback with a V6 on a 16’ boat

[altamate]

If you don’t have enough setback and prop height the chine walk is more difficult to manage. The 21” pad bottom Checkmates want 14-16” of setback. It takes less for the smaller boats and you can drive them with none, but the easiest way to drive them fast is with enough setback. If the reason to put 200hp on a Predictor is to find the top speed, then you might as well add the setback or you end up stuck at ~70-75mph where the chinewalk overcomes the drivers skill. Only 6” on a Predictor won’t be enough for most people, yes there are guys with seat time that can do it, but most can’t. If the reason for 200hp is holeshot instead of top speed, then you don’t need all the setback.

The Checkmate forum is not very busy anymore, but there use to be at least a question a week like this on all the 16 -21ft pad bottom Checkmate outboard hulls and the answer was always the same. The guys that ran 80-90mph had enough setback. Everyone else complained about the chinewalk.

[Check_Jo3]

Wow never thought that they would need that much. 14"-16" is really getting back there! (It would look pretty sweet though) I always thought that 8-10 would be ok for my Dads 21 Starflight when/if he ever wanted to restore it. Come to think of it.. the starflight does seem to want to go straight to chine town when you start winding it out with the motor right on the transom. Positive trim and a big rooster back there. But his steering is sloppy when which definitely does not help. The 1st pic is his 21 from many years ago now.. I think this was 68 mph. I always thought that the new 72 mph top speed was a little slow when he said that it would do 65 all day back in the late 80s and he had what he called a Yamaha "220 Special" on it. 2nd pic is OC MD on Assateague right near the inlet 10 years ago.
500609500610
As for the predictor I don't think I am going to want to try and squeeze every last bit of mph out of it (then again when it's finished that could go right out the window) Would starting with a 6" j/p then going with some spacers if more setback is needed? In my head, the end goal is a boat that can cruise with nice manners and be able to blast up to the high 70s when the conditions are right (i.e. when my pops gets wise in his boat lol). Anyone know the setups on Greg G's or Great East Predictors boats? I am not going to attempt to strap a 225 back there like Great East and go 90 but I am wondering how far back he had his.

Again I can't thank this forum enough for the info.. hopefully I can provide some good content when I get this thing going. I should be picking it up today!

[bbezok]

I currently have 91 Pulse 185 that came with a 2.4 175 Mariner on a CMC Jackplate (5.5" setback) and L&S 2" Spacers for a total of 7.5". Chine walk was crazy at a top speed of 60. Swapped power head to 2.5 200, added solid mounts and a Slidemaster 8" Setback on the transom, then used the CMC Plate for a total of 13.5" of setback. Now I don't have a low water pickup as of yet so engine height was limited but completely changed the attitude of the boat.
best speed was 69.23 on GPS running a 25 Trophy Plus and was manageable to drive so the extra setback and solid mounts were a plus.

[StubbyCheck]

I’m running a 6” manual plate bolted to 4” spacers on the back of my Pulsare 1600 bowrider which shares the same basic hull. My Yammy Excel weighs in just over 400lbs. The higher I go with the motor the better she handles at higher speeds. I do have some bounce between 25-30 mph, but most guys seem to fight that with a V6 on the back of this hull regardless of setback. Next season I’m gonna see if a drag plate helps any.

[Check_Jo3]

Thanks for all the replies. Looks like a good starting point would be a 8" plate and most likely add some wedges, and maybe a sand bag in the nose to help the porpoise when going slower. XstreamVking recommended them in another thread I found. Anyone else had good luck running the wedges?

[Great East Predictor]

I've got a predictor that has had a few engines in it: 2.4 Bridgeport EFI, 2.5L 225X, 2.0L 150hp and now a 2.4L 200hp. I've run 4.5" of setback, propshaft about even with the pad on all the motors with good results. I would recommend some kind of weight in the nose as they do like to porpoise quite a bit a lower speeds. Mounting the battery up there is a good amount of weight. The 150 ran low 70's, 200 runs low 80's and the bridgeport and 225x both got it into the 90's pretty easily.

[Check_Jo3]

Great East, what kind of props where you turnin and was your setback a hydraulic plate or manual?

[Great East Predictor]

I have a hydraulic. I've tried quite a few props: chopper, trophy, lightening et, bblades blaster, promax, txp ot4, tempest and a cleaver. It seemed to like the trophy, txp ot4 and chopper the best.

[StubbyCheck]

I’m running a Trophy Plus and it seems to be a really good every day prop, although I may find a little more speed next summer with something else, we’ll see.

[Check_Jo3]

After doing a little number crunching on the effect of a heavier motor farther out from the transom I have found the following.
Using the transom as the base reference point. and assuming that the original engine may weigh roughly 300 lbs and the point of mass
would concentrate roughly 6" [0.5 ft] off the back of the transom. A moment of 150 ftlb is created.


Now, lets round up a couple pounds for the weight of the 2.5L engines to 400 lbs. using a 6" jack plate would put the new mass
out at we'll say 12" [1 ft] from the transom. This creates a moment of 400 ftlb off the back of the transom.. the weight of the jack plate
also makes an moment. Using data on Bobs machine 6" hydraulic jack plate it has a weight of 71 lbs. We will make the assumption that the
weight is at 3" [.25 ft] off the transom. This adds a moment of 17.25 ftlb.


This brings the total moment to ~420 ftlbs to round off the number. To counter this and get the balance back to what the
300 lb engine put on the boat, we'll need a moment in the other direction of 270 ftlbs (420 ftlbs minus the original 150 ftlbs).
Adding 22.5 lbs 12' from the transom (toward the bow) would solve this using this theory. A battery is somewhere around 40 lbs and should
be a good start


This solution method may not entirely fix the problem as the prop is in a different position in the water relative to the boat and changes
the leverage on the hull but strictly from a weight perspective this is a good start I think.


Has anyone gone about calculating the counterweight of a bigger engine in this way or is this way whack? This is getting away from the original subject but its still kinda relevant I suppose.

[creeljd]

If you don’t have enough setback and prop height the chine walk is more difficult to manage. The 21” pad bottom Checkmates want 14-16” of setback. It takes less for the smaller boats and you can drive them with none, but the easiest way to drive them fast is with enough setback. If the reason to put 200hp on a Predictor is to find the top speed, then you might as well add the setback or you end up stuck at ~70-75mph where the chinewalk overcomes the drivers skill. Only 6” on a Predictor won’t be enough for most people, yes there are guys with seat time that can do it, but most can’t. If the reason for 200hp is holeshot instead of top speed, then you don’t need all the setback.

The Checkmate forum is not very busy anymore, but there use to be at least a question a week like this on all the 16 -21ft pad bottom Checkmate outboard hulls and the answer was always the same. The guys that ran 80-90mph had enough setback. Everyone else complained about the chinewalk.

I concur, this is very good advise.