Z302 top speed with 496 Mag/Bravo 3
 

Hello there fellow Mariah owners. It's been quite some time since I've been on the site. I hibernate over the winter but with the ice starting to melt, I just pulled my Z302 out of storage and started getting things ready for the spring launch later next month. I just bought this my 2001 Mariah Z302 last year and was excited to own a boat that is spec's for 53 - 58mph. For years I had to put up with my Brother-in-law scootin' past me in his Doral 245 Sunquest which does about 51 mph. Unfortunately, my top speed (on the GPS) is about 50.5 mph which means he continues to get by me albeit now just a crawl of about .5mph faster. With the spring coming up, do we have any other Z302 owners out there with the 496 mercruiser/Bravo 3 combo that are getting top speeds higher than 50mph. I have the original brochure for the boat which specs it at 53-58mph. I'm getting 5000rpm at WOT which is the confusing part. I could see if I was unable to hit the spec'd WOT RPM but that doesn't seem to be a problem. I love the boat and it handles like a dream but just need to somehow squeeze a couple more mph's out of her.

Note in my profile picture that the boat rides very level even at top speed and I therefore seem to be pushing a lot of water with my bow down although the drive is trimmed right out to it's limit. Any boat I've owned in the past only has the last few feet of the hull in the water when trimmed out at top speed.

Thoughts/suggestions????

Re: Z302 top speed with 496 Mag/Bravo 3
 

My 302 will do 53 on gps no matter if I have 2 guys or 11 (7 adults and 4 kids). I had 24 p props and have now moved up to 26p props looking for a lil more speed as well.

I also installed a set of smart tabs in hopes of getting up on plane a lil quicker.

How much fuel do you typically carry ? I know that makes a HUGE difference on acceleration in mine. Full tank, she's a tank, 1/2 tank and it's much quicker.

Re: Z302 top speed with 496 Mag/Bravo 3
 

got any more pics of your boat ?

Re: Z302 top speed with 496 Mag/Bravo 3
 

Thanks Oregon Dunes. Mines the same, it doesn't matter if its just me or me and 10 others, 50.5mph is all I can get. I'm quite sure the props are 26". Does your bow come up out of the water so that you're not pushing so much. I do have more pictures and will post them as soon as I figure out how...:shakehead:

Re: Z302 top speed with 496 Mag/Bravo 3
 

btw.....mine has a 454

I can trim it out so the nose it higher, but there still 20 feet of boat pushing water

Re: Z302 top speed with 496 Mag/Bravo 3
 

Damn...I've got the 496 8.1L V8 with the Bravo 3. Captain's call Thru Hull and trim tabs to get 'er up quick. I don't even really need the tabs since it kicks right up out of the hole. I only really use them for balancing the load when I have a bunch of people on board. It may be due to the 496 that I really don't have issues with the full tank vs. 1/2 tank of fuel but damn, I want to get it up into the mid 50's.

Re: Z302 top speed with 496 Mag/Bravo 3
 

I just verified that I have 26" props. Since I'm hitting 5000/51000 rpm at wot, do you think I should try a 28"?

Re: Z302 top speed with 496 Mag/Bravo 3
 

great looking boat. what is the black ring on the shower door ? you have different grab handles on the swim step then me.

Re: Z302 top speed with 496 Mag/Bravo 3
 

Thanks. She's definitely a head turner. I love the set up of the 302. I've always wanted one and was lucky to find this 2001 for sale last year. Due to an injury (broken back) the previous owner had it stored away since 2005. I bought it with just 160 hours on it and got it for a steal. Because it ws stored away for so long, it was totally overed in dust, dirt, grim and mould which turned off most potential buyers. After a closer inspection, I determined that underneath all of that dirt was a brand new boat. I bought it, took it home and spent about 20 hrs of cleaning time and a couple grand on new tops, carpets, etc... And voila, an "almost new" Z302.

The black ring is the base of a pedestal mount gas grill.

I did some more research on the prop issue and have determined that I should update my existing 3 blade configured 26 pitch bravo 3 with merc's new 4 blade configured 28 pitch Bravo 3. I've also been looking into the "Signature Four by 4" Bravo 3 replacement by Hill Marine. Albeit a fairly new prop (out since last January) they have a guaranteed satisfaction return policy. The "Signature" prop has four blades on both the front and rear prop unlike the merc with just 4 blades on the front and 3 on the rear. Not sure which route i'm going to take at this time but interested in hearing from any others that might have had some experience with the "Signature" prop by Hill Marine.

Re: Z302 top speed with 496 Mag/Bravo 3
 

I stepped up to the 26 this winter and have not had it in the water yet.

Keep us posted on your prop selections.

Re: Z302 top speed with 496 Mag/Bravo 3
 

So what pitch were you getting the 53/54mph on? It'll likely be another 4 weeks beforenthe ice is off the lake here (Ontario Canada), so it'll be May before I can get things tested. After doing a bit more research, I think I'm going to give that 4x4 blade configuration by Hill Marine a try. Will keep you posted.

Post some pics your 302 when you have a chance. It would be interesting to see any differences that might exist (ie: grab handles, etc...)

Ciao for now...

Re: Z302 top speed with 496 Mag/Bravo 3
 

This is the topic I was looking for. I hit the rev limiter on my Z302 with 502 Mag MPI B3 and 26 pitch propset fairly easily with a lighter load. I find the boat to be fairly trim sensitive. Note that the microwave, TV, freshwater and sink systems are gone and I try not to carry around too much other extra stuff. Bennet 12 x 16 sport tabs have been a great addtion, albeit a tight fit.
From what I have been able to determine, swapping in a 28 pitch propset might be just as good as anything, especially versus tuning my 26 set, going to a cupped 26 set, or going to a Bravo 3 XR set with one 4 blade. I don't know anything about other B3 options.
What I need is to stay off the rev limiter when trying to air it out, but, more importantly, get better midrange cruising speed and mileage, and possibly even better top speed. Hole shot is not a problem.
I intend to do a GPS speed run in a week or two, and am looking for a regular 28 set to swap out to repeat the GPS run. Either the speedometer lies or the boat is pretty fast already. GPS will tell, and I'lll post results and look for results on other swaps.

Re: Z302 top speed with 496 Mag/Bravo 3
 

I was running the 24p bravo 3 merc props that came on it and could hit 5100-5300 with ease no matter what. Kinda scared me a bit running the motor that high, but it didnt seem to mind it.

Ive now installed the 28p bravo 3 merc props and smart tabs, but havent had it in the water just yet to determine the difference.

Here are some pics

http://img.villagephotos.com/p/2006-...2/IMG_0216.jpg

http://img.villagephotos.com/p/2006-...G_0197-SML.JPG


Fridge where the TV used to be.
http://img.villagephotos.com/p/2006-...2/IMG_0218.jpg

http://img.villagephotos.com/p/2006-...G_0269-SML.JPG


Rearward facing speakers for our floating friends
http://img.villagephotos.com/p/2006-...G_0276-SML.JPG

http://img.villagephotos.com/p/2006-...2/IMG_0287.JPG

http://img.villagephotos.com/p/2006-...2/IMG_0289.JPG

http://img.villagephotos.com/p/2006-...2/IMG_0291.JPG

http://img.villagephotos.com/p/2006-...2/SDC10493.JPG

http://img.villagephotos.com/p/2006-...2/SDC10593.JPG

Re: Z302 top speed with 496 Mag/Bravo 3
 

Hi fifth's impression,
I have had a 1999 Z302 since new. However it has a 502 mag mpi(425hp) and a bravoIII. The props have 26" pitch and the outdrive is 2.00. When new it would do 55 mph on a full tank with four people. It would do 57 mph with about 70 gallons of gas and one person. However after about 7 years and 200 hours the speed began to decline until it was down to 47 mph. However my RPM also dropped off to 4600rpm at WOT. (Yours didn't?) I found several problems over the years each had some impact. First be sure to check the bilge. The Z302/300s have a false bottom below the bottom under your engine-which appears to be the bilge. It holds about 20 gallons of water without showing in bilge area. That 20 gallons on a full gas tank really bogs it down. . I have also had low fuel pump pressure, a faulty knock sensor which will retard your ignition, and a hook on the boat bottom (a slight arch from the transom to about 18 inches forward of the transom). I had all these problems at once which built up over time. The hook had a 4 mph impact. It essentially forces the nose down as if the trim tabs were down. It was caused by the trailer bunks not going all the way to the transom and partially by arching bunks. After I repaired all those issues it began slowing again last summer(280 hours). This time it was bad valve springs which are a common problem on older GM big blocks. I have not gotten it back in the water since but hope to have it in by mid-march. One more consideration- if the boat sat for a long time your compression rings could be stuck causing it too loose compression. Adding Seafoam in the carburetor can hurt. The only way to be sure of valves and ring condition is to do a compression check.
It does seem strange that you are only getting 50 mph at 5000RPM with a 26" pitch prop-- unless your outdrive is trimmed out too much and the prop is cavitating. I find that I am at optimal plain when the spray is coming from a point on the bottom edge directly below where your bimini top fastens to the aft windshield frame bracket.
I have performance curves(speed vs rpm) for my boat if you want them and I also made a curve of the gas volume that tells you how much gas is in the Z302 tank versus gas gage indication. I was very surprised to see how much less it holds on the last half-tank of gas.

Re: Z302 top speed with 496 Mag/Bravo 3
 

How do you get that 20 gallons out ? Does it drain completely when you pull the brass plug ?

Re: Z302 top speed with 496 Mag/Bravo 3
 

I am pretty close to wrapping things up on my Z302 and hopefully she will see the water sometime in the middle to end of May. Engine going back in this weekend if work does not call.

I can recall when all was good running with my boat that she never really broke free from the drag of the water and most of the time it seemed to ride from midship back at full trim and never really was able to loosen up to gain more speed. I brought a handheld GPS along on one of my trips and the fastest she would go was 57 mph at 5200 rpm and at was running a set of 28P Bravo Three's. I have a picture that a friend took of my boat running at speed and remember by looking at the picture a good portion of the boat was still in the water while trimmed out which equates to a slower speed. I am going to check the hook on my bottom before I drop her back in the water and will take pictures detailing the hook or lack of one. The Z302 is not a speed demon by any stretch of the imagination but is able to handle a lot of different conditions while running at those higher speeds.

Re: Z302 top speed with 496 Mag/Bravo 3
 

Hi oregondunes, Yes it drains completly when you pull the plug. But the void behind the hole can accumulate junk from the bilge and all the other drains in the boat. So I occasionaly push a bottle brush in the hole and pull out junk.

Re: Z302 top speed with 496 Mag/Bravo 3
 

That makes sense to me now. I looked in the engine bay the first time out of the water and there was nothing there. But yet when I trailer-ed it up out away from the ramp and pulled the plug, another gallon or five came out. Wondered where that had come from.

Mt boat sits on a trailer all the time now and lives indoors. I did notice the first couple of trips last fall misc small stuff would come out. I wonder if you remove the mid cabin floor hatch you could spray water that way and "flush it out" better should there be stuff lodged in that area.

Im picking my boat up from the shop today. I had all the nicks and dings repaired in the gel coat and then off for canvas replacement.

My graphics guys were hot on it yesterday taking measurements and looking at my ideas. I should have a mock up next week.

Re: Z302 top speed with 496 Mag/Bravo 3
 

This is what I found in the pipe and under the cabin floor leading to the bilge while cleaning out my boat after purchasing my Z302.

http://www.mariahownersclub.com/foru...0_dsc00017.jpg