captiva 226 slow to plane

jajoco

Recently bought a captiva 226 and have not used it much but with only 2 in the boat it seems slow to plane.  It has a 5.0 volvo with a 21 pitch prop.  I thought about going with a different prop since most of the time will be towing but would still like occasional top end speed.  Would I be better to stay with my prop and add trim tabs?  I'd appreciate feedback.

mvn

Here's some output from an optimal prop calculator I created in Excel.  This example is for my boat.  The blue line is theoretical boat speed versus pitch and the magenta line is RPM versus pitch.  My WOT range is 4600 to 5000 RPM.  For input, you just need a drive ratio and a prop efficiency number.

You can see from the output that I can run an 18", 19" or 20" 4-blade prop while keeping the WOT RPM within the allowable range.  In my case I sacrificed top end speed for low end acceleration because I tow more than I cruise.  For cruising, I would go with a 20" 3-blade on my setup.

Mark

MarkB

I can't comment on the engine, but I can say trim tabs will help a lot. 

mvn

Without knowing the ratio of your stern drive,  it's hard to specify a prop.   Any way to find out? It may well be slightly over-propped. 

My 226 on the other hand has a Merc setup.   My optimal setup is an 18" 4-blade stainless with Smart-tabs.  Lots of grunt for towing yet still has a respectable top end. 

Mark 

jajoco

Thanks for the comments.  MVN can you tell me where I can find the stern drive ratio.  So you are satisfied with how your boat planes with your prop and tab setup?  What type of Smart tabs do you have?  Thanks.

JC290

That prop pitch seems quite big to me 

212rowboat

The pitch does seem high, bit even if it is it's barely so... My 212 w/4.3 carb'd can twirl a 21p three blade just fine, which leads me to believe a 5.0 should be fine with the same... 

It's so close that smart tabs would be a huge help, or, even venting the existing prop to allow it a head start before water tension closes the vents for basically the same purpose....  trim tabs are a fix, vents are a bandaid and only useful for someone wanting to retain the top end while adding some hole shot, and on a prop that's only a little bit too steep. 

Am I crazy here? 

jajoco

Thanks jc290 and 212 rowboat.  I'm considering adding smart tabs and if it's still slow out of the hole I'll check into switching out the prop.

mvn

Is your Volvo an SX single prop drive?   I forget where the ratio is located but I can have a look at one tomorrow.  Do you know what your wide open throttle rpm is?   What is the max rpm rating of your 5.0?  This will tell us if you are over-propped or not. 

I'll get you the model number of the tabs and a few photos as well. 

Mark

mvn

There should be a tag on the upper portion of the drive.   For a V8, you should see 1:43, 1:51 or 1:60.   

Mark

nhsd

My 212 has the 5.0 carbed 220 HP engine and I run a 21 pitch prop mostly. It is a 1.62 Mercruiser outdrive though... I put on Smart-tabs which did improve the hole-shot, but mine was pretty good to start with. I wanted the tabs to allow a slower speed while maintaining plane.

mvn

Here's my Smart-tab setup.  Some will say that they are mounted too close to the drive but they work just fine....no issues whatsoever and the performance improvement is VERY noticeable.

Mark

MarkB

For getting up on plane, that would work fine, but do they work efficiently to trim out any listing while on plane?

212rowboat

MarkB said:

For getting up on plane, that would work fine, but do they work efficiently to trim out any listing while on plane?

they're not designed to do that.  they're designed for hole shot on a boat used for multiple purposes. 

MarkB

But certainly if they were on the outer edges, it would help trim the boat level as well, right?

212rowboat

If they could be adjusted, but they can't... The drag is going to dictate position, not the level... There have been times when I wished they could, believe me, but.... they are fantastic on a boat in the 18'-24' range, where true trim tabs are a questionable investment, that gives you the opportunity to do water sports and top end, low planing for economic cruising or slow speed handling... And also for allowing the same prop to be used for all of it... They're around $100 or so and do the job well... Adjusting attitude isn't one of them, though, attributes, that is. 

MarkB

Oh, so they are manual? Do they have springs keeping them in the downward position? 

212rowboat

Yup.. little strut/shock thingies... They apply a preset amount of pressure and water tension folds them alone.  Some have adjustments where the shock mounts, altering the leverage point and in effect adding or reducing the required weight to depress them, But that's it. 

212rowboat

I like mine a lot... And the added maneuverability they add at idle speed is undersold.  

mvn

MarkB said:

Oh, so they are manual? Do they have springs keeping them in the downward position? 

Mark, 

See photo above.   The black thing is a gas strut. 

Mark

jajoco

Thanks for all of the feedback.  I ordered nauticus smart tabs today and hope I see some improvement getting on plane.  The  boat is at the lake so hopefully I can get the drive ratio this weekend. The engine is a fuel injected 5.0 volvo GXi.

212rowboat

You'll like em ja... I've never heard a boater say "dang I wish I'd never installed those"...  

MarkB

So, if you turn quickly, does it affect performance? The theory I'm thinking of is the side opposite of your turn will lift out of the water, causing the tab to drop in the water (maybe), making it harder to turn.  Obviously thinking only at higher speeds. Notice that at all?

212rowboat

Naw, man... You're over thinking it..

Water tension based on speed/drag are going to flatten those things parallel to the hull as soon as they overcome the strut pressure... It'll hold them there until speed lowers and the strut can overpower the same water tension.  In a hard bank, while at same time dropping speed, it may play a role, bit not a huge one.  Unweighting the boat by banking that hard and lessening the tension may allow them to drop some, but I bet its hardly any... The stern is planted firmly, now like the bow.  On a bass boat or overpowered boat, where the water cuts right at the transom, I'd figure them a bad idea.  I've not met a rinker that runs that hard yet.   

69fastback

I've been researching these smart tabs a bit. I have an '03 Captiva 232BR, Merc 350 Mag/Bravo III, and while I'm "okay" with how my boat performs, I'd like to get get a little less bow rise, especially when it has 600 lbs of gas, and 6 or so adults in it, and a little lower plane speed for when I'm pulling my kids around. 

Looking at their website, I'm not sure the original Smart Tabs are right for my boat, and it looks like I may need the Smart Tab IIs. Does anyone have them on a 232 with my set up? The title lists the dry weight at 4500 lbs, and it holds 70 gallons and 12 people. I figure I normally operate it between 6000-6500 lbs. Also, I believe that I'll have to mount them close to the outdrive, like pictured above, but judging by the comments, that seems sufficient. 

69fastback

Just in case anyone is researching the smart tabs, Greg at Nauticus recommended the SX10512-90 for my 232. I'm going to go ahead and order them and see how they do. 

Madcow

I would go traditional tab vs smart tabs.

With Smart Tabs you have no on the fly control. Your stuck with where there set.

I bought a set of Lenco tabs and they are phenomenal. I can change there position at any time for load balancing, get out of the hole or even low speed cruising from switches in the cockpit.

The best investment by far for my boat which is a 2004 Captiva 232.

69fastback

I see a lot of people discredit the Smart Tabs, when in fact, they've never actually used them. Most of the time, it's people with Bennett or Lenco type tabs, and have no experience with Smart Tabs. I took my boat out for the first time last weekend, after installing Smart Tabs (Captiva 232), and I must say that they work as advertised. The bow rise is cut in half, the ride is better, slower plane speed, and better top speed are all things I've seen. 

The post above implies that they are non adjustable saying, "your (you're) stuck with where there (they're) set," which is false. The Smart Tabs are constantly adjusting to the conditions, without pilot input. They're often referred to as "non adjustable," which isn't true, because they're always adjusting. 

And I'm not saying that bennett or lencos aren't better for some situations, but the Smart Tabs work as advertised, and I'd bet people like the gentleman who posted above have never used them.

Michael T

Are you guys talking about two different types of "smart" tabs. Lenco makes "smart" tabs that automatically adjust to the load but they are very expensive units that adjust independently from starboard to port to manage loads on cruisers. They are also called "auto glides".  I have regular Lenco tabs that are infinitely adjustable at the helm and are amazing. I can set them up for a hole shot or at any angle from port to starboard to manage differences in "side to side"  loads or even wind shear. I agree that self-setting trim tabs would be a lot better than nothing but there is no way they are as effective as trim tabs that can be constantly varied while underway by the captain.

mvn

Agree with MT but  the Nauticus Smart tabs are set and forget.   They work great on smaller boats and don't require fiddling.  Once again,  you're not trying to do the same thing as the more capable Lenco or Bennett tabs but they are a **** of a lot better than a hydrofoil.

Mark

69fastback

Exactly. I was referring to the Nauticus Smart tabs, which are set and forget. They are inexpensive, and while they may not work as well as a tab adjustable from the helm, they DO WORK as advertised. My Captiva 232 planes at a much lower speed, has 75% less bow rise, considerably less bow wander at idle speeds, and will level out a minor list from passenger loading. For $130 and < 1 hour to install, they do an excellent job.