Got my Grandsport w/300XS finally dialed-in

[Jr in Jax]

UPS delivered me a brand new 28 PP Yamaha copy Drag4 last light and I took it out for testing today. I ended up with what seems to be a perfect match. The Holeshot was great with no bounce and the handling was very smooth with cruise speed at 68 at 4400 RPM. I burned 10 gallons going 65 miles. The taller engine gives it a bit of wobble when I hit a big wake offcenter, but I have now gotten used to it at 32 hours [it has rained every day here]. The punch is great at midrange and revs almost instantly.

 

[David Lanham]

Thanks for posting the update.

I've got a few more ?s if ya don't mind

Does the boat sit noticeably deeper with the heaver motor on the back?

How more getting on-plane bow rise does it have compared to your previous promax?

6.5 mpg with 300HP, that's great!! My Prosport / 225X at best gets 5 mpg.

 

[Jr in Jax]

The boat with a full 30 Gallon tank, cooler full of ice & bottled water, spare prop and a 15 pound anchor, floats in spring water with the rear rubrail about an inch above the water. I can climb in from the rear with no water getting inside [I am 6' @ 265#]. I was getting a lot of bow rise with the 32 drag 4 and had to get a couple of CMC negative trim shims to try and tame it. With the new 28" drag 4, I get about the same rise as my Promax SS [15" mid] 225 but a much faster launch [no bounce at all]. I love the CMC shims [takes a half hour to install] since they hold my bow down going through the no wake zones and give me another 2 MPH through them. The 300 never even breaks a sweat to cruise at 70 MPH and rides better than the 2.5 [except the occasional wakeboard boat wake wobble due to the taller 20" midsection].

 

[RiverRocket]

I have a 300XS on my XB21 Prosport. I'm kicking around a dedicated sport boat. I would move my current 300XS to that boat. I'm interested how the boat runs above 90. How does the GS handle at those speeds with the XS?

Thanks in advance.

 

[Jr in Jax]

I have only had it to 90.3 with 4 people in it and it handled well. I have not felt comfortable enough to go above that by myself. My top speed with the promax was 95 GPS and all three times it was with three people in the boat. I am sure I am getting old or else I would have found out what WOT speed was two months ago.

 

[procomp]

90 with 4 people in a grandsport getting good fuel mileage sounds like a pretty good package

 

[Jr in Jax]

I hope to head to the Suwannee on Saturday and might find out just how fast it will go since my Wife is not going. The Merc online calculator says that with 10% slip, 28 pitch prop, 1:62 gearcase and 6300 RPM is 99 MPH. With the 32 before it should have made 105 and felt like maybe it could.
My boat's bottom is not in the best shape from many-many thousands of miles with the trailer bunks wearing my gel coat. I hope to get Jack Barsh to re-gel coat the bottom this Winter. I am still interested in the "elusive" 24' Grandsport….

 

[harrells]

Don't hold your breath on that one. I don't think that one will ever see production. If merc would do a 15" on the 300R I think I might try it on the GS. Not any heavier than my 250XS.

 

[whipper]

Jr does the 300xs have the same or better hole shot as your Promax did?

 

[whipper]

My guess is a 30 drag 3 with slight tip cup is going to be a winner gs 300xs . The drag3 has better hole shot and midrange than the drag 4 with and 2.5 but better deceleration manners. Tip cup to go with the added torque for bite.

 

[Jr in Jax]

James,
The 28 drag 4 gives me a perfect hole shot. It will instantly come out of the hole with no bounce at 1/2 throttle. The acceleration is fast enough that my speed reaches the point that I have to leave the trim alone [I wish the trim was just a little faster] in order to steer before I reach optimum trim.

The Promax would have been better I had known to install the negative trim shims from CMC . I think almost any Allison would benefit from them.

My Promax had a OK hole shot but nowhere near what I am getting from the 300XS/ 28 Drag4 combo now. The 32 was just too much wheel for the 1:62 gearset but the 28 is perfect. I was running for short distances in the low 90's yesterday but the Suwannee was covered with 50-100 floating logs every mile due to the high water. There were almost no other boats due to the logs. I hit two small ones myself [no damage]. I burned 12 gallons on an 80+ mile round trip.

 

[whipper]

You have me drooling Jr. did you add anything in the
bow for weight ? Also did you move your battery to the front forward in the rear compartment? Sound like an awsome setup!!

 

[whipper]

You running 1\4 below?

 

[RiverRocket]

You inspired me to run my boat light and cleaned out more like a sport boat. Tried two passes and got up to a little over 97 and gave up because I felt like I was a first time driver washing the sides. I like the boat so much more when its loaded up to fish. I can get it to run way faster loaded. Someday I will have to spend a week in it cleaned out just to get the hang of it.

 

[Jr in Jax]

You inspired me to run my boat light and cleaned out more like a sport boat. Tried two passes and got up to a little over 97 and gave up because I felt like I was a first time driver washing the sides. I like the boat so much more when its loaded up to fish. I can get it to run way faster loaded. Someday I will have to spend a week in it cleaned out just to get the hang of it.

I like the way mine handles with some weight in it [the pad sits deeper]. Just a slight quartering crosswind will cause it to tilt off the pad when it is light. A little larger/wider pad seems like it would take more to tilt it.

 

[Jr in Jax]

You running 1\4 below?

I actually am able to run slightly above. I have fidgeted with my hydraulic jackplate and lowering my GC 1/2"-3/4" makes the boat want to rock.
I can see no difference in water pressure either. I have two half-dollar size hot spots on my midsection and I watch my Gearlube carefully since some of the earlier XS sportmasters had an overheating problem.

James, be sure to buy a set of the CMC Negative trim shims, Darius was the one who sold me my first set and I added a second set later to get it just right. Since you sometimes pull the tube, you will love the holeshot. Let me know how you like it.

 

[whipper]

JR do you have a pic of your GS with the 300xs. i would love to see how she looks on there!! Im searching for one this winter. Last question how do you find not having a ratcheting case? With less lip probably not a problem i suppose as it is the lip that makes the bow ride so high and the fall to the keel has a steeper angle when settled. Not as fast with a 2.5 buy about 5 mph but manners are way less touchy when slowing down.

 

[Jr in Jax]

I will try and get a better pic with it sitting in the water. To tell the truth, I can not tell the difference in the gearcase. Maybe I am such a poor driver that I can't tell what it felt like before. The only thing I have noticed is that it can wobble more when hitting a quartering wake at high speeds. It is as smooth as any four stroke.
Its gas mileage certainly makes it much more fun on very long high speed cruises. It gets slightly better gas mileage than my Honda Turbo PWCs [which are fuel sippers].

 

[whipper]

Wow looks great on there JR!!!!! Nice very very Nice!!