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Questions regarding Setup on 21' Starflite

dkramer

Member
As most of you may or may not know I have been overhaulin my 21' Checkmate Starflite. Here's the setup:

1988 21' Checkmate Starflite w/ 2005 Merc 250xs 20" Torquemaster with Nosecone. 10" CMC Hyd jack plate. Motor is bolted on bottom holes to jackplate. I am running a 24p Trophy Plus. I took it out on Sunday and was running at 5600-5700 rpm around 68mph. I thought for sure I would have to go up in pitch but that does not seem to be the case. Also the boat sits a bit lower than it used to due to the weight of the new motor. I feel that the rear platforms may be dragging, so I am going to take them off and see if that makes any improvement. Also my buddy has a 23p Trophy Plus which I am going to give a try and see if I can get the rmps up a bit closer to the 6300 rpm rev limiter. I know some of you guys have similar setups ar setups with 200's running in the 70's. I thought that I should have been able to hit at least 80. Any info would be appreciated.


Thanks,
Dave
 

Boston Predictor

Well-known member
Ive never had a starflite but I dont think the swimsteps are the problem.
I think you might need more setback and you might gain a few more mph with a chopper. goodluck
 

dkramer

Member
setback

If I go with anymore setback I'm gonna rip the transom off the boat and need a 15"mid...LOL JK that's for the advice.
 

Chris E

Well-known member
i doubt the platforms are an issue, they will be out of the water at planing speed. are you getting it up enough on the jackplate - with a decent amount of set back, you may need to be on the higher holes of the plate.
 

dkramer

Member
up all the way

I have the jackplate mounted to the transom int he top hole of the jackplate and I have the motor mounted to the jackplate in the bottom hole (motor is as high as it can go.) I could get the jackplate up more by using the lower holes but I think that will end up stressing the transom way too much.

Dave
 

Boston Predictor

Well-known member
Either way there is going to be alot of stress regardless if it is 2-3'' up or down. The prop has to be pretty level with the V to gain more rpms. Some folks say that 12''or more would be ideal runing the propshaft level or above the V on a starflite. I would concider bracing the transom if you are worried about stress because even with 6'' setback over time the transom will flex and crack.
 

dkramer

Member
Agreed

I had a bracket fabricated on the inside of the transom from between the stringers in the shape of a U bolted through to the knee braces with plates ont he outside of them. I think next is to have something fabricated for the top that could attach to the 2 upper bolts through the splashwell, going through the splashwell down to the lower plate. I will try raising the plate a bit higher and see how it goes.

Dave
 

aaronmt

Member
OK I have a 87 starflite with a 20 year old YAMAHA 225 thats ran 74.3gps last summer bone stock. I see some definate issues wrong with your setup ( I learned the hard way and expensive way last summer). First thing is as high as you can go on that cmc 10" isnt high enuff I had mine off numerous times and tried all sorts of extentions from cmc to bobs machine, the cmc 10" just doesent work on that hull period. I got a Vance mfg 12" it starts off higher at it lowest point then the cmc goes at its highest, its a bit lighter then the cmc and fairly inexpensive and believe me to get that hull out of the water you need 12"s. Second im not sure what you have for bow foam but theres a wall in the bow with foam behind it, it may or may not be wet. I removed the wall and the foam as well as the headliner and painted it all dark grey looks alot cleaner and save some weight. Your on the right track as far as props go I tried all sorts and the starflite loves the trophys. The 24p trophys are for some reason a strange bird from what ive been told they rev more then they should so when you goto a 25 it falls flat out of the power curve. When i tried the 24 my revved like crazy, so what thats telling me is your motor must be burried like crazy. Ive found prop shaft height at 1 1/2 inches to be just right for everything on that boat. Last summer at 74.3 i was spinning a 25p trophy plus at 6000-6100rpm. I hate to give the bad news to you but there just noway that jackplate wwill work i spent half the summer trying it just wont get high enuff or provide enuff lift for the starflite hull(trust me on this). Some guys even say 14" but I say 12" is enuff. I think by simply installing a water pressure guage changing the jackplate and removing the excess bow foam eight you should be able to spin a 25p or maybe 26p trophy to 80mph. PS. I just got my powerhead back so I will hopefully being putting up some new numbers myself Its making 260hp at 6800rpm now so im shooting for low 80s myself:bigthumb: . I hope i didnt ruin your nite but I did exhaust all options on the cmc it just doesnt work I sold mine on ebay real fast so im sure you can as well. Aaron
 

Mark

Well-known member
I would agree with the others. You need to get more height. Propshaft 2-3" below the Vee.
What is the gear ratio? At 1.75 you should be spinning at least a 25" prop, maybe 26" or even 27".
And again, don't take off the swim platforms, they are not dragging.
 

aaronmt

Member
MY swim steps are not in the water at all when underway, come to think about not a whole lot of the boat is!!!!!!:bigthumb: Aaron
 

aaronmt

Member
If you could post a pic of the transom and the motor I bet will naile this down real quik I have to think that boat should be running neer 80. What elavation are you at im at sea level so that helps me if your at say like denver you wont run as fast as you wouls at sea level? Aaron
 

dkramer

Member
bad news

Thanks for the input. I agree after looking at the picture of the vance that it sits way higher than the cmc. From what I gathered they don't have a 12" Hydraulic? Is there a jackplate that is comparable that is hydraulic? My boating conditions change where I boat and I go from a bay that can turn into condtions like an ocean and also a river that can be a smooth as glass. So i need the ability to drop the motor a bit at any given moment or raise it up and fly. I can see where the motor can't get up high enough to really go. I have a manual water PSI as well as smartcraft so I should be good to go in regards that.

Dave
 

dkramer

Member
sea level

I'm at sea level. Let me see if I can post a pic tonight, the wife lost the camera overvoard this past weekend, LOL. My gear ratio is 1.75. Like you guys said the platform are out of the water when flying but under when put putting.
 

Boston Predictor

Well-known member
You could make a spacer like Mark did and that will give you the extra setback.
Thats a nice looking starflite! where's the windshield?
 

dkramer

Member
out for powdercoating

Windshield is out for powdercoating. Just finished up today and should be picking it up this weekend.
 

F150GT

Member
I have found set back is the key to speed on Starflights, Height is also critical and as you add setback you also must add height. At 16" back I am running the prop shaft 1/2" below the pad and still maintaining good water pressure with a stock lower unit. I custome made a set back bracket to distribute the load on the transome. All the strain is distributed to farther out on the transome. 72mph with A Yamaha Pro-V 200 25P Yamaha 3 blade prop.
F150GT
 

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Mark

Well-known member
I have found set back is the key to speed on Starflights, Height is also critical and as you add setback you also must add height. At 16" back I am running the prop shaft 1/2" below the pad and still maintaining good water pressure with a stock lower unit. I custome made a set back bracket to distribute the load on the transome. All the strain is distributed to farther out on the transome. 72mph with A Yamaha Pro-V 200 25P Yamaha 3 blade prop.
F150GT
Hey F150
That is very unique. Most guys butcher up the splash well trying to put in extra supports. Am I looking at your pic right? Have you mounted pipes out to the side to the transom. Are they bolted on above the swim platforms? Is there a set higher and lower or just up top? What size and guage material did you use.
 
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