Jubilee 21' not planing out please help
 

Hello fellow Mariah folks,

My father in law is a new Mariah Jubilee boat owner. He has a 21' Jubilee with an Alpha 1 mercruser sterndrive. We tried to use the boat this past weekend and with 6 adults and 1 child the boat would not plane out. It is running so heavy and just drags in the water (stern way down and bow way up). I am assuming that this is not normal with 250 hp this rig should get up and drive well. We need your help. I believe it is a mismatched or incorrect prop issue but not sure. He has a 3 blade standard (not stainless) 17/15 prop on the boat. That's all the info I have. We tried to use the trim tabs to bring the bow down but the boat was too sluggish to even do this. Boat was half full of fuel as well. Thank you for any suggestions.

Dan / SILofnewboater

Re: Jubilee 21' not planing out please help
 

Hmmm... where to start....

A "17/15" prop??? Really?? That 17" prop diameter (if accurate) is way too large for these boats. It should be around 14 3/4" with a 19" to 21" pitch. I would suggest a 3 blade aluminum 14 1/2" or 14 3/4" x 19 pitch prop as a good all-around prop for these boats. A step up would be a 4 blade 14" 3/4 x 20" pitch SS prop.

Are you sure your outdrive trim is working correctly? (Dont rely on the gauge) Trim down/in to start and then trim up/out as the boat planes. I would check its movement while the boat is out of the water first.

Re: Jubilee 21' not planing out please help
 

Hi mikeyt-- Thank you for the response.. As far as I can tell the trim is working fine but as I expected the wrong prop is on the boat. Would a 14" x 20 4 blade work as well as the 14 3/4 you mentioned. I cannot find a 4 blade 14 3/4 online anywhere only 14 x 20 4 blade. thanks again

Re: Jubilee 21' not planing out please help
 

Not sure where you are looking for a prop but 14 1/2 & 14 3/4 diameter props are quite common. Try this site

While you are at it, you might want to read at least 1 or 2 of the STICKYS at the top of the Prop Talk Forum. just for a little self-education.

Re: Jubilee 21' not planing out please help
 

I have the same boat wit the small V8 and found that the 17 pitch prop was the best for my use. I'm able to pull tubes and skiers with no problem, and will top out around 42-45 mph which is fine for me. I had a 19 pitch, but the hole-shot wasn't good enough IMO for skiing, but my be fine for you. If your budget allows for it, also consider electric trim tabs. I frequently have 6+ people in the boat, and they will level it out perfectly, even if everybody is sitting on one side. Also they dramatically help getting on plane quickly. I wouldn't have another boat without trim tabs.

Prop I use: SOLAS Rubex Aluminum 14-1/2 x 17 RH 9513-145-17. Trim tabs: LENCO 9x12 (Easily self-installed)

https://s22.postimg.cc/40r4sdsfl/IMG_8555.jpg

Re: Jubilee 21' not planing out please help
 

Assuming the boat has a 5.7 engine? That boat should jump out of the water with a 17 pitch prop assuming your trim is working and all the way down. Don't spend too much time worrying about the prop and focus on the two most common causes of this problem. Either the engine is not running properly or you may have water in the hull. Take the boat out with no gear in it and only one or two people on board. Listen to the motor and also take note of your rpms. If the motor sounds like it is bogging down or sounds out of time then there may be some issues that need to be addressed. This doesn't mean you need an engine rebuild but could be serious issues.

If the engine checks out then extra weight from water in the hull should be eliminated. You can check for soft spots in the floor or the easiest way is to weigh the boat. Most stockyards or city dumps have a large scale that you could weigh the boat on the trailer. This will give you a clue as to whether you're trying to push extra weight. If you're several hundred pounds over the expected weight of the boat that could explain the difficulty getting on plane. If you can provide the year, model and engine for your boat we can find the dry weight.

Remember that the boat probably ran fine with the current configuration at one time. This means something significant has changed and these are the two most common. Props really come in to play when you're trying to get a better holeshot or tuning for top end speed. My thought is the prop is a little undersized for that setup.