Performance Boats Forum banner
1 - 20 of 30 Posts

·
Registered
Joined
·
436 Posts
Discussion Starter · #1 ·
My friend is trying to dial in his 28 Howard Deck boat. He bought it used with a shorty lower. He thinks that he is not getting enough trim. He was thinking that he should lower it with a spacer to give more leverage to lift the bow with trim. Right now the center of the prop shaft is 2.25-2.5 in below the center pod which is the lowest point in the hull.

To all the Howard 28 deck owners: Where is your prop shaft in relation to the center pod? What has worked best for you?
 

·
Registered
Joined
·
6,120 Posts
This weekend is the Howard boat get together in Havasu. So you may not get a reply right away. Unless Havasu Dreamin is awake. :D
 

·
Floatin dirty
Joined
·
4,831 Posts
How about some motor specs and speed numbers? What makes him think that he needs to lower his drive? Howards seemed to be dialed in pretty well right from the shop depending on the motor package. Whats the boat doing that leads him to believe he needs to modify it? What prop is he running? Some props give bow lift like Hydromotive and other give stern lift or run neutral.
 

·
Registered
Joined
·
436 Posts
Discussion Starter · #4 ·
The last owner put a shorty lower when he upgraded to higher hp engine....we are trying to figure out if the shorty was a good idea. I understand that there is a balance between less drag with the shorty and more ability to get bow lift with the stock lower. He can't tell if it is a 1" or 2" shorty either... so he was thinking of trying a couple drive spacers.

Basically he feels like it is not getting enough bow lift compared to his past 26ft cat. He has 650hp with a 30p bravo prop on 1.5 gear and gets 84 @ 5200 rpm (WOT) with 2 on the boat and light fuel.
 

·
Ultra 27 Shadow
Joined
·
1,870 Posts
The last owner put a shorty lower when he upgraded to higher hp engine....we are trying to figure out if the shorty was a good idea. I understand that there is a balance between less drag with the shorty and more ability to get bow lift with the stock lower. He can't tell if it is a 1" or 2" shorty either... so he was thinking of trying a couple drive spacers.

Basically he feels like it is not getting enough bow lift compared to his past 26ft cat. He has 650hp with a 30p bravo prop on 1.5 gear and gets 84 @ 5200 rpm (WOT) with 2 on the boat and light fuel.
Those numbers do not seem that bad if you ask me, JMO.. Especially for a deckboat. I would call Howard direct like previously mentioned or PM KAP on the boards here. He knows that boat better then anybody when it comes to setup.
 

·
Ultra 27 Shadow
Joined
·
1,870 Posts
The last owner put a shorty lower when he upgraded to higher hp engine....we are trying to figure out if the shorty was a good idea. I understand that there is a balance between less drag with the shorty and more ability to get bow lift with the stock lower. He can't tell if it is a 1" or 2" shorty either... so he was thinking of trying a couple drive spacers.

Basically he feels like it is not getting enough bow lift compared to his past 26ft cat. He has 650hp with a 30p bravo prop on 1.5 gear and gets 84 @ 5200 rpm (WOT) with 2 on the boat and light fuel.
Also if he drops the drive lower he will lose RPM and will most likely have to drop in pitch on the prop.
 

·
Registered
Joined
·
465 Posts
Buddy of mine is running the Merc. 600 with the Whipple re-tune, standard XR turning a 28 and has run 94 GPS with a light load.
 

·
Registered
Joined
·
436 Posts
Discussion Starter · #11 ·
Also if he drops the drive lower he will lose RPM and will most likely have to drop in pitch on the prop.
That is another thing....he plans on labbing the prop. If the rpm goes down but the prop slip also goes down then he has the right prop to lab. if his drive is in the right spot then he could lab the prop and cup the tips for bow lift....or if dropping the drive allows the boat to lift more the RPMs may stay the same with greater speed and it would be time to up the pitch and labb a new prop.
 

·
Registered
Joined
·
436 Posts
Discussion Starter · #12 ·
Remember with that reprogram on that 600 he is now probably making more than 650 HP. I do not htink your buddy is that far off it at all. Again, JMO.
You may be right....could be that it is just hot and not getting the best # possible
 

·
Ultra 27 Shadow
Joined
·
1,870 Posts
You may be right....could be that it is just hot and not getting the best # possible

That is definitely another reason. I know in the summer heat I lose a solid 3-5 mph with my setup along with 300-500 rpm with the heat. If it were me I would wait till it cools down to see how it does. The only benefit I see by a spacer is that he will roll on plane faster, but if the boat does not have an issue with that now then that really is not benefit.

Mike
 

·
Premium Member
Joined
·
729 Posts
Standard xr, stock height, 600 sci with estimated 670 hp due to stage 1 recalibration. Last time I was out with average load (Three men, two in shape and one fat one) 86mph with 28 maximus 5 blade. Temperature was 114-115 degrees. Fastest speed I have ever ran was in colder weather 92 mph same prop. I have run a 28 4 blade and a 30 4 blade and they don't seem to perform as well for me. Typical speeds with two guys half tanks 95 degrees would be about 87 to 88 mph. Before I would make any changes I would try a five blade. I know that the five blade stresses the drive more but after running both props it is a risk I am willing to take. Go out to the Howard sorta reagatta going on right now and you will have alot of advice on tap. Keep in mind that I have a 5800 rpm rev limiter.
 

·
Registered
Joined
·
436 Posts
Discussion Starter · #15 ·
That is definitely another reason. I know in the summer heat I lose a solid 3-5 mph with my setup along with 300-500 rpm with the heat. If it were me I would wait till it cools down to see how it does. The only benefit I see by a spacer is that he will roll on plane faster, but if the boat does not have an issue with that now then that really is not benefit.

Mike
It gets on plane easy....it just seems to lack bow lift. Trim setting 0 is prop shaft even with the boat....can't feel any more lift past 2.5 or 3
 

·
Registered
Joined
·
316 Posts
Standard xr, stock height, 600 sci with estimated 670 hp due to stage 1 recalibration. Last time I was out with average load (Three men, two in shape and one fat one) 86mph with 28 maximus 5 blade. Temperature was 114-115 degrees. Fastest speed I have ever ran was in colder weather 92 mph same prop. I have run a 28 4 blade and a 30 4 blade and they don't seem to perform as well for me. Typical speeds with two guys half tanks 95 degrees would be about 87 to 88 mph. Before I would make any changes I would try a five blade. I know that the five blade stresses the drive more but after running both props it is a risk I am willing to take. Go out to the Howard sorta reagatta going on right now and you will have alot of advice on tap. Keep in mind that I have a 5800 rpm rev limiter.
how low is the prop shaft from the bottom
 

·
Premium Member
Joined
·
729 Posts
how low is the prop shaft from the bottom

I do not know and I am not near the boat now. It is stock height, I would suggest calling Howard and they can help.

I would not start with modifying props. I would try the 5 blade. I think you will notice a big difference.
 

·
Premium Member
Joined
·
3,136 Posts
Standard xr, stock height, 600 sci with estimated 670 hp due to stage 1 recalibration. Last time I was out with average load (Three men, two in shape and one fat one) 86mph with 28 maximus 5 blade. Temperature was 114-115 degrees. Fastest speed I have ever ran was in colder weather 92 mph same prop. I have run a 28 4 blade and a 30 4 blade and they don't seem to perform as well for me. Typical speeds with two guys half tanks 95 degrees would be about 87 to 88 mph. Before I would make any changes I would try a five blade. I know that the five blade stresses the drive more but after running both props it is a risk I am willing to take. Go out to the Howard sorta reagatta going on right now and you will have alot of advice on tap. Keep in mind that I have a 5800 rpm rev limiter.
Dan, who was the fat guy, LOL
 
1 - 20 of 30 Posts
Top