Trim Tab size and boat performance - Maxum Boat Owners Club

Chillaxintoo · 04-03-2017, 07:37 PM

I am looking for anyone who has experience changing out their stock trim tabs to enhance their boats performance. I have a 98 2800 SCR single engine 7.4L MPI with Bravo III drive. With 22P props and a 5-6 person load the boat is very difficult to plane. With 2 on board if does fine and operates within the WOT range but load it down and I have to send 3 below deck or it absolutely will not plane. I have been looking at a set of 4by4 props to help with the hole shot but someone mentioned my trim tab configuration on another forum so I thought I would look into it. According to Bennett's website a boat my size should have 24X12 or 30X9 tabs on it. I haven't measured them but I'm sure they're either 12X12 or at most 18X12. I would like to know if anyone has done this and what tab did you choose and what were the results. Quicker planing? Lower Cruising speed/RPM? Better tab response side to side?

mmwjr · 04-03-2017, 10:25 PM

Bennett also sells a kit to add end wings, don't recall the official term that bolt to the side edges of the tabs that folks have reported help as well. Tom (Tabman) from Bennett posts to many forums including this one. Try sending him a PM and have him post a response to this thread.

Chillaxintoo · 04-03-2017, 10:30 PM

thanks, I have seen that name somewhere, maybe here. I'm just wondering why would Maxum put such small tabs on the boat if they need to be bigger to function properly? Did they think the extra surface area would create too much drag and the engine wouldn't have enough grunt to overcome it?

mmwjr · 04-03-2017, 10:36 PM

Quote:

Originally Posted by Chillaxintoo

thanks, I have seen that name somewhere, maybe here. I'm just wondering why would Maxum put such small tabs on the boat if they need to be bigger to function properly? Did they think the extra surface area would create too much drag and the engine wouldn't have enough grunt to overcome it?

Who knows could just be to save money but lots of boat builders have installed small tabs. IMO a single engine heavy boat is going to suffer in time to plane with 5 or more adults based on my experience. Props and tabs help but torque of one engine on a boat over 8000 lbs will notice the load.

My 2400 SCR with a 5.7 planes slower with over 4 adults.

Chillaxintoo · 04-03-2017, 11:14 PM

Yeah, I lot of mass and a lot of water to push. I'm just trying to make it perform the best it can. I'm not looking for runabout performance, just respectable

Tabman · 04-04-2017, 12:02 AM

Yes bigger tabs can really help. To help best I would like to know the current size and if at all possible see a picture of your transom.

They will do all you are looking for.

Tom McGow
Bennett Marine

Chillaxintoo · 04-04-2017, 12:23 AM

Boat is a 1998 Maxum 2800 SCR 9'8" beam, 6500# dry weight, 28' long. I'm 250 miles from the boat and it is in the water so a transom pic might be tough. I'll see what I can find. The tabs that are on it are the factory originals. I think they are 12 X 12 if I recall correctly. I can tell you that when I adjust them I get very little side to side adjustment. In your experience, do larger tabs help when your boat plows a lot and struggles to plane when you have a larger passenger load?

Chillaxintoo · 04-04-2017, 12:36 AM

This is not our boat but is a 2800SCR, tabs look to be the same size as our and location is similar.

Chillaxintoo · 04-04-2017, 12:46 AM

2000 Maxum 2800 SCR Miami FL for Sale 33193 - iboats.com

Image didn't seem to load, this is a link to the photo

Tabman · 04-04-2017, 01:05 AM

Those are Lenco tabs and they do look like 12 x 12s. 18 x 12 would be better and would really help with what you want to do.

But you would have to move the actuators to be in the middle of the tab side to side.

If they were Bennett I would suggest 18 x 12 with 3 inch drop fins to get the most lift, but they are not really compatible with Lenco actuators.

Tom
Bennett Marine

Chillaxintoo · 04-04-2017, 01:11 AM

thank you for the insight. I was thinking I would need to go much bigger and was worried the extra drag would rob a lot of power from my already marginal powerplant. I'll have to look into the cost of converting to the bennetts. I assume I can buy new actuators, would their pump work or do I just need to get it all new?

Tabman · 04-04-2017, 11:36 AM

You're really going to have to have someone look at the boat, since when I looked up that year and model boat I found it had Bennett hydraulic Trim Tabs not Lenco electric ones like in your picture.

5931894_20160908121708278_1_XLARGE

This boat appears to have larger Tabs with the drop fins I mentioned.

Bennett does make electric trim tabs as well. So it really depends on what you actually have before I can make specific recommendations.

Tom McGow
Bennett Marine

Chillaxintoo · 04-04-2017, 12:01 PM

Thanks for the info, the pic a sent was really just to give and idea of location and size. I was able to find a pic I had of the engine bay that shows the reservoir or the trim tabs and it clearly has a bennett label on it.

Chillaxintoo · 04-04-2017, 12:02 PM

Thanks for the info, the pic a sent was really just to give and idea of location and size. I was able to find a pic I had of the engine bay that shows the reservoir or the trim tabs and it clearly has a bennett label on it.

Hope that helps.

Tabman · 04-04-2017, 12:21 PM

Then, if the Tabs are really 12 x 12, and you are willing to move the actuators, installing two 18 x 12 with Drop Fins would help a lot. Part Number TPA1812DF (you need two each) ask a dealer about pricing.

I would recommend that you confirm the size Tabs that are on the boat before you purchase the new Tabs.

Tom
Bennett Marine

Chillaxintoo · 04-04-2017, 01:39 PM

thanks Tabman for all the info. I will definitely have them measured before I order anything. If for some reason my marina does feel it's practical to move the actuators do they make drop fin plates in the 12 x 12 size? Would they be worth swapping out?

Tabman · 04-04-2017, 01:51 PM

Actually we make "Bolt on" Drop Fins that will fit 12 x 12s. Part Number DF12 you need 1 each of that number to convert the 12 x 12s to drop fin.

Chillaxintoo · 04-04-2017, 02:09 PM

guess you guys really think of everything. It sounds like I really need the 18 X 12's but it's good to know I have another option if that's not practical. Thanks for the info.

shrew · 04-05-2017, 03:55 PM

Chillaxintoo..

When you have 5-6 people on board....

1) Where are they all sitting when you attempt to get up on plane?

2) Do you have coolers onboard? If so where are they located?

Chillaxintoo · 04-05-2017, 06:20 PM

Shrew... It's a cruiser so everyone is in the cockpit area, sometimes there's a cooler, sometimes not. It would also be in the cockpit and yes I know that is the worst possible way to try and plane a boat underpowered, undertabbed or not. My question was whether getting tabs closer to Bennett's recommended size would provide me the additional lift I need to get it to plane in those less than ideal circumstances. My other concern was whether or not the increased surface area of the larger plates would create more drag than my engine could overcome. I realize it won't jump out of the water but I don't want to have to make my guests jockey around the boat when I'm trying to get on plane if there is a way to avoid it. Lowered cruising speed would be bonus if I could get it but not my main concern. I'm guessing that if I get very little side to side movement when adjusting the tabs now it's a sign they aren't big enough. Tabman gave me some great options and I'm thinking of doing that along with going to a 4X4 prop setup to get some additional lift and a better hole shot.