Handling of a 2015 305 grady with twin 300 yamahas

[Tony Z]

I just got the boat and am learning it's running characteristics. It runs completely different than my former Contender And Intrepid. I know it's no speed demon but it in 2 footers I cannot get a comfortable cruise up around 30 MPH. It's has 15 1/2 by 17 props. It seems squirrelly and moves around alot. I have tried more bow down trim digging the motors in all the way. If I pull it down to 25 MPH It runs better. Is it me or is the hull configuration just not made to run at 30 MPH in choppy seas. Love everything about the boat but need to get some help on figuring out this out. I frequently make long runs offshore hense the contenders and intrepid.

 

[everwhom]

Do you have trim tabs? My 330 Express (basically same hull but longer) is very sensitive to trim. In a head sea or tight chop, even 2 feet, it rides far batter with the bow down so the sharper angle sections of the variable deadrise hull is in the water.

 

[Fishermanbb]

It should just fine at 30. I have the same hull (306) and cruise at 32 in anything reasonable without issue. Also had a 2000 Marlin( same hull) with no issues. It is not even close to the same hull as a 330 ( had that boat as well). However , it will not ride like an intrepid or contender due to the variable deadrise and the beam. Those boats have a sharper entry angle and narrower beam v LOA than a GW. If it is “Squirrely” you may have it trimmed up too much. First, try trimming down the engines to the midpoint of the trim range and see if that helps. Working with the tabs may also help. Make sure the motors are mounted on the correct hole for your application. The 30Ft. GW hull is an absolute tank ( which is why it is not a fast or fuel efficient hull). It is an older hull design for GW. First check the basics above. Then, if you can’t get the running attitude where you want it you’ll need to look further at hull deformity, etc (HIGHLY unlikely).

 

[JJF]

Try three or four bars of engine trim along with four or five bars of trim tab trim.

 

[family affair]

If all of the above doesn't help, check your engine alignment.

 

[drbatts]

Same boat, Same engines. Don't use the trim tabs other then for side to side leaning. Make sure the engine is tilted all the way down, throttle up until the boat jumps out of the water. Get your rpms around 4500 or so, then start trimming up with the engines until hit the sweet spot. You will feel it and hear it when you get there. You can also look at fuel consumption to help with trimming the engines. I cruise 30 knots and around 4700-4900 rpm on most of our runs. At this speed the boat eats up 2ft chop like a rottweiler eats a T-bone steak.