Formula boat porpoising
 

Anyone here got experience with Formula boat porpoising???

Ours will do so with the smallest amount of trim on the outdrive.

I have never seen a boat tolerate such a low amount of trim (up) from full down.

If I use the trim tabs (maybe 3 - 5 dots on the indicator) it will bring the porpoising under control and allow greater trim up, but its a funny balance.

Wondering if its unique to the hull (Formula 270 BR) or maybe the stock props are not well suited to our loading and use.

BTW its a Mercruiser 8.2 Mag/Bravo 3 twin prop (stock)

Any thoughts are appreciated.

Yup....
 

...here in the software sales world, we call that an "undocumented feature"....

I have a 2016 270BR with the same motor as yours. First time driving it home from the dealer the bow started bouncing up and down uncontrollably....what the heck...??? The test drive model never did this...

Phoned the dealer literally from a full-stop in the middle of Meredith Bay. Was advised to put the tabs down about 3 lights on the meter. I keep them there all the time now and have never had a problem since.

Porpoising = out of trim?
 

Can't say directly to your boat, but we often see/hear boats going by porpoising "Out of trim" is the immediate comment. Try putting the drive all the way down and using only trim tabs for minor adjustments especially side to side. There may be a "neutral drive trim position that isn't all the way down, but close. It should be easy to find, which is why I believe, usually all the way down. Otherwise , after lifting engine for trailer or shallow water, you and other owners would have difficulty finding a repeatable proper position. Recreational boats are not planned for that--should be easy and repeatable.
What did the dealer say? Owner's manual?

In my case, outdrive was all the way down. I don't monkey around with moving the outdrive up and down, (unless of course it's shallow water)...that's what the trim tabs are for.

Interesting, sounds pretty similar.

Are you also running a Bravo 3/stock props?

Thanks!

p.s. in the software coding world we call it a bug and add it to the next patch ;-)

In my decades of boating I've never driven a boat that didnt perform better with a modest amount of trim up on the drive, it always helps get the hull out of the water and you feel the steering response change significantly.

This is the first time all the way down is the near perfect setting.

That said, I have never owned or driven a Bravo 3 before,,,

Called factory tech line and they said trim all the way down, then tap trim up maybe 2 times. Seems odd to drag so much hull in the water, but it sounds like thats how these boats are built.

Go out on a calm day, start with the tabs all the way up, to take them out of the equation..... The get up on plane and go to about 3500 rpm... that is where most people tend to cruise... then slowly trim the boat up, see how it re-acts, the the tabs up and out of play, you should find the balance point, where the bow will bounce with the least little ripple.... Once you find that point, trim back down a little, and that is likely where you want the drive when you out and about...

Then put the trim tabs back into play, and use them as your supposed to, to control the attitude of the boat for the given conditions....

Tabs and trim on the drives are for different things, most people don't know how to use them in conjunction with each other... so the best thing is to find where you want the drive, and leave it there, and use the tabs to adjust the boat from then on out.....

What about the trim limit switch and trim gauge possibly being out of adjustment?

Maybe the tucked in setting is still 2°-3° to far up.

Starting there it doesn't take much more trim to reach the porpoise point.

I suspect there is a way of measuring this.

I am surprised that anyone would operate an outboard or I/O boat without making trim adjustments on the drive. I use mine constantly.

When bringing the boat to cruising speed I always leave the drive down. Once I have an established speed I lift the drive so that the bow will rise. This accomplishes two things: Your speed and RPM will increase slightly with the same throttle setting and the ride will be much softer since the bow is not hitting every wave you cross. Generally, it will bring about the front third of the boat out of the water and your MPG will increase with less drag.

I only use the trim tabs to keep the right/left attitude of the boat level and the necessity for that depends greatly on the loading of the boat. The best setting for the trim tabs is all the way up to eliminate drag on the boat. The ability to do that depends greatly on the loading and the hull design.

I realize that everyone has their own way of doing things but this is what has always worked for me over the last 50 years and about 15 boats from 18 to 34 feet. (Two were jet boats and you can ignore using a lot of your experience with a jet boat)

This is exactly what I did.

What surprises me is how how little trim up this boat will tolerate.

Most boats I have driven never porpoise, you will simply just over trim an lose performance.

Clearly the combination of hull design, length, power and the ability to transmit that power into thrust have created the ability in this boat to porpoise.

Also it appears that Formula has picked an engine/outdrive angle that is very neutral. It neither allows you trim down to an angle that lets you plant the nose in really rough water, nor does it appear to need much trim up to reach the designed planing attitude.

No complaints, just not what I have experienced in the past and seems interesting/unusual to me, as most boat I have driven usually have a pretty wide range of trim they operate/tolerate. I honestly have no reasonable basis to say if this is common or uncommon, I only know what I have see personally and for my this is a different experience. And the experience that MeredithMan describes is pretty much how our boat performed, so it would seem to me there is nothing wrong with my boat per se, nor my surprise by the way it performed compared to my personal past experience.

Thanks!

I dont think there is a problem, its more of a perception issue of how limited the range is that this boat runs well in.

Older/smaller/less powerful/differently designed boats seem to allow/tolerate a wider range of outdrive trim, and it appears this one runs in a narrow range.

But I think you are on to something in that maybe Formuls should be looking for a trim gauge that better displays the useful range for this boat. The gauge in my boat is clearly suited for a different boat that allows/tolerates a wider trim range. its basically a worthless gauge as it doesnt display useful information, the range of trim movement displayed is almost impermeable.

So maybe in reality you have helpped me better understand part of my concern, I'm in part basing part of my original concern on what I see in the gauge, very little movement on a gauge with a wide potential range. Like putting a 20,000 RPM tach on a motor that mostly runs under 4000 RPM. Not super use/helpful.

Thanks

Very similar to my experience and thoughts.

Well stated!

Thanks for the reality check.

Hogback...
 

You don't mention the age or repair of the boat. It could have been stored on a misaligned trailer or misaligned rack that's affected the keel—inducing a "hogback".

Its a new boat with ~35 hours on it.

One can never rule manufacturing defect or transportation or storage problem, but based on what MeredithMan and the factory tech said, it sounds like it just the nature of the boat to run more hull in the water, need less trim, and the factory trim gauge not being well matched to the range the drive travels.

Oh and new owner of a different boat and outdrive than he has had in the past.

That all said, I do wonder if the boat would react differently with a different prop. Virtually every boat I have ever owned performed totally differently and MUCH better with a good aftermarket prop.

Open to any recommendations you guys may have for a good prop set for a Bravo 3. And feel free to tell me there is none better for this setup. It would not be my experience, but I'm learning there is still a lot learn about these newfangled boats ;-)

Does the Formula use a stepped hull? A friend has a Monterey with a stepped hull and it won’t tolerate more than a very small amount of trim. Single prop Mercruiser.

Not really. Drive trim up decreases the wetted hull area. Trim tabs can be used to level your boat due to unbalanced weight port to starboard or can be used to let your boat's deeper V toward the bow break slop. My lake boat has a 24 degree hull at transom but is way steeper toward the bow- in 3-4' winni chop I use tabs down to get the bow down. Use your tabs well and you can get dock space all over the Lake when many are sitting home!

Original Formula was a 2001 260SS 496 B3 drive. Replaced that with a '09 260 SS Volvo 8.1 duo-prop.

Same hull, both boats, but not sure if the newer 270 Formula has the same hull design. I almost immediately start trimming the drive up after taking off. I feel the vibration go away, most likely resulting in better mpg, and a slight increase in speed. Trim tabs to balance the boat only.

From what the OP described, I trim up a lot more than he does. It only porpoises if I bring it way up.

That said, for him it seems like it's the nature of the beast. If you trim it up 'til just before porpoising and you still feel vibration, maybe there's an issue. For me, trimming up removes the vibration but no porpoising.

Good luck finding your trimming comfort zone.

You mentioned new Boat with 35 hours. Not to try and simplify things, but couldn't you just take it to who you purchased it from and say " I spent X amount Dollars on this boat. Please show me the perfect way to drive it. " I would think that would answer most question. Make them actually work for their money.

Formula Porpoising
 

The only time my bird do that is when the outdrive tab is too high. I would lower the outdrive tab until the boat attitude is fine. Normally I use the trim tabs to level the boat. Or create a bigger wake for surfing. Both trims all the way down.
When taking off the outdrive tab is down to keep the bow down. When I hit speed, I normally raise the outdrive tab until there is an increase in rpm. Rarely do I trim to the point of porpoising. If I do I back down.
I only use the trim tabs to level the boat from Port to starboard. Sometimes if I have a lot of people and full tank, trim tabs all the way down can help you get out the hole.
Since you have the Bravo III I suspect you have a lot of torque (6 blades vs 3). I have driven Formula SS with Bravo III and never porpoise.
I have a Bravo II. I switched from 3 blades to 4 with much better overall performance. I urged anyone with a 3 blade to upgrade to 4.

Check the back pin on the trim cylinder where it mounts to the drive their a spacer in there that could be in the wrong position ..

Sounds to me that Formula has taken the stance that most people buying their boats, don't have a clue as to how to trim and adjust the handling of their boats. Thus, they have made things harder on those that understand how to make a boat perform they way we want.....

What this means, is that to really be able to trim and control the handling of your boat, you need to make more drastic adjustments, so that you get proper trim response... the problem is that would start to void a new boat warranty....

I would talk to a dealership or two, and see what can be done... The wrong answer from a dealership would be, "it is what it is"..........

Sounds to me, the the drive isn't really properly placed, thus you are porposing, because, you boat is riding on the hull further up, and the cavitation plate of the drive, instead of the rear pads of the hull, like it should....

We are surfing behind a Formula?

You are not crazy. The trim on the 270 is VERY sensitive.

The porpoising has been documented on BoatTest when they reviewed the 270

CTRL-F "porpoise"

https://www.boattest.com/oem/386/boats/3651/0/

Well I think we have clearly established its just how this boat runs as delivered.

A better trim gauge would have helped me better understand whats going on, and I plan to share that with Formula.

I also cant help but wonder if a different prop set would have any impact.

As BroadHopper said a few posts back, in a regular single prop Bravo drive switching from a 3 blade to a 4 blade prop is well worth the cost. Wondering if its the same with a 2 prop Bravo III drive. Its a big expense to change 2 props but if the end result is a noticeable change I might be willing to pop for it.

Not that there is any connection to the present problem. Several decades ago on Cape Cod I knew someone with this happening. I don't remember the make of boat, however, they added an extension of several inches, possibly 6", to the hull. The situation was resolved. I do not know but the boat may have been stored incorrectly causing warping of the hull. Weird.

__________________________________

I am a retired workaholic and continuing aquaholic

I'm not sure a new prop set up would yield a big difference. The 8.2 with B3 out of the box is already a great pairing for that boat. What you've got here has more to do with the engineering/design of the boat itself.

I hear you though. I would be frustrated too if the Gauge showed a very low trim position and she was still porpoising (or close to it).

There were already a few comments about the sender/limit switch. +Another Vote for checking the sender. You could have the dealer check and re-calibrate the trim sender. That could possibly help you gain some better readings on the gauge. Those sender units are notoriously crappy (break all the time). Something could be going on there (even at 35 hrs).

Summary
 

OK. I'm not a Formula guy,but it now sounds like a hull/drive mismatch that can be overcome by very careful use of trim. "C'est possible?"

Hummm,,,, Based on what I have learned from you all and other reading, it appears to be a case of a different hull than I have had in the past, and learning to drive this particular hull.
It also appears that Formulas run more hull in the water/wet than other brands, and that appears to be by design. Which is fine now that I know it, and as a plus, it makes for a very good/very solid ride in Winnipesaukee weekend water conditions. It is clearly slower than other brands, which surprises me given the 8.2 Mag engine but it is also a long and heavy boat with no creaking and rattling that I have seen in other boats. So I guess these are trade-offs and with the Winnipesaukee speed limit and the way we use our boats I don’t need 50+ MPH speed, so not being a high speed boat is not a problem for me. Sounds funny even saying that as I recall when 35 or 40 MPH was fast ;-) Guess times change.

It does appear to be a poor selection of trim gauge, as the gauge range is too wide and does not best display the limited trim range this hull allows.

And I still wonder how Bravo 3 drives respond to aftermarket prop upgrades? Is it similar to other drives, or not worth the cost???

Thanks to all for your thoughtful insight

Stepped hull
 

As asked previously, does this model have a stepped hull? I had a Larson with a stepped hull and had the same problem you describe when trimming up the outdrive. I learned very quickly, stepped hulls do not need and should not be trimmed by raising the outdrive, only use the tabs. The stepped hull already raises the hull out of the water and trimming the outdrive is too much. I loved the stepped hull, better gas mileage, very little bow lift out of the hole, no need to use tabs to get out of the hole and very quick to get on plane.

I would try a set of Hill Marine 4x4 props and see if it helps. the downside of not being able to trim up is poor fuel economy. Maybe the extra stern lift of the 4x4s will keep the boat from ever starting to porpoise.

porpoise
 

It did not appear in photos and reading BoatTest that it has a stepped hull but based on the BoatTest write up as previously mentioned it appears this hull acts like a stepped hull in that very little trim is needed or should be used.

I had two boats with stepped hulls and the single prop one liked plenty of trim with the a high lift 4 blade prop. The one with a Bravo 3 liked about 20% positive trim but was not very sensitive to trim.

I dont think so, looks very traditional deep-v

https://scontent.fbos1-2.fna.fbcdn.n...97&oe=5E3D664E

I still think you'll go down a rabbit hole if you start tinkering with props. Dual 4 Blades might help but they might force you to give up some mph at cruise or at the top end.

This is a beautiful brand new boat with only 35 hours. I'd do a few shots of trim up as advised, use the tabs to correct when needed and just have fun. Also if you load passengers and gear more towards the bow that will help too. I would put some more hours on her get to know each other better and then decide what you want to do later about the props.

I think that test report says it all.

While you could try new props, I don't believe you will find it that rewarding. I have reproped a few boats, and never noticed, and effect on the effectness of trim. Gain a better hole shot, or faster speeds is really what re-proping a boat does for you.

My personal opinion, is don't get caught up with the trim guage. the are known to be problematic. I really believe the most economical solution to your problem is as I stated before... Put the tabs up, and spend time understanding the boat, with just the drive time. Figure out where you want it, and then leave it stationary and let the tabs help you with everything else.....

Now if you are interested in spending money to get to a better situation, I suggest looking into bigger trim tabs.... the with lengthen the running surface, you should be able to trim up on the drive some more, and then use the tabs to settle down the porposing...

Good advice there.

I don't use a lot of trim with my 260. In certain circumstances I will trim up and use the tabs to settle it down, typically when it's really rough. There is a sweet spot that gets the drive line running nice and smooth, that's what I seek mostly.

Generally I think the Sun Sports are heavy in the butt end, trim tabs are a must for sure. I had one of the switches fail once and I wasted no time replacing it.

Agreed Jason, even though that Formula measures as a 27, the hull really is not as long as it appears with the boat sitting in the water when you look at the image posted by the OP.

Isn't that like all boats today? A modern "210" is actually a "190" with 2 feet of swim platform. It bugs me so much how brands do that today with their naming conventions.

I'm glad some still try to avoid it though for the most part. Formula is one. Like this "270" actually has close to 27 feet of fiberglass underneath. I think it's listed as 28.5 on the spec sheet with the extended platform you have here.

My 2008 Sea Ray 240 Sundeck is 26'4" or so.

The newer ones are about 2' smaller.

This has been my experience with my Formula 37PC. Very little, if any up-trim is required (I trim up just a small amount until there is a slight increase in RPM's). Trim tabs are used to make minor adjustments to maximize fuel efficiency and ride quality.

For what it’s worth I have a 2015 290 with twins and I have experienced this in the past. I will say the boat drives beautifully with drives all the way down all the time, but I feel there was a bit of extra drag and probably sacrificing a bit of fuel efficiency. I could very slightly trim up (maybe 10%) without issues but didn’t feel I was getting full benefit but it drove fine as well. If I went a little higher (20-30%) it would porpoise and not drove well. I went out with a friend one day and started playing around and went to 50-60% and it drove fantastic. It was much higher than I thought was logical but it literally floated on water and cut through everything with minimal slam on the hull even in choppy conditions. Don’t be afraid to play around - we were at about 3200 RPM/30ish MPH in this case which is a great cruising speed for the boat. Hope this helps a little.


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Good catch!

Thought the end to end measurement of the boat is well over 28' the running surface of the bottom ends well before the end of the swim platform, maybe 4'

The layout makes for an interesting balance and centerpoint for weight.

It had a great ride in Winnipesaukee water conditions.

We just moved up from a 23' Caravelle Interceptor with a good size swim platform pushing its end to end length to 25', but for the few feet difference the Formula is a totally different boat.

Much heaver, better rough water ride, more interior space, but MUCH slower overall and doesnt really loosen up like smaller boats at higher speed and higher trim levels.

Not complaining at all, just observing its a very different experience than all my other previous boats.

So far we LOVE it!

Its always good to end up being happy with a purchase of this level :cool:

Interesting, I would have never expected it to respond better at a point of trim past where it porpoised.

As several folks here have suggested, I still need to spend more time getting to know it and trying different combinations.

Based on your experience, I may need to think beyond my previous experience which told me to stop adjusting the trim level up when I started to experience porpoising.

Sounds like a good reason to get in more seat time next season :D

Hi I just PMd you on this subject.

Just responded, happy to share what I have learned and its all positive!

Outdrive vs trim tabs.
 

Formula owner since 1988. I learned a lot about porpoising and other alimonies. First off, I use the trim tabs to level the boat port and starboard. Contrary to popular belief, the Trimming the right tab button only works on the left tab and vice versa. Thus I use the right button to raise or lower the port side and the left button to affect the starboard side.

It is the outdrive trim that I use to prevent porpoising. I start out with the trim in to get up on plane. Once at speed, I would trim out until either the engine speed increases or the boat speed decreases.

Only then do I adjust the 'attitude' of the boat, it varies depending on water conditions, weight distribution, as well as weight. If it is porpoising I touch the trim level down and porpoising stops. It's not rocket science but getting 'the feel' takes experience.

Mostly the same as I have found, except that mine has the Mercruiser Activetrim option and that took some additional time to figure out how to use that as opposed to the manual process you describe.

What I found works best for me and how we load and use our boat, is to dial in a fair amount of trim tab, maybe 4 - 5 bars on the indicator (both sides) and then I let the Autotrim take control of trim angle and I give it full authority.

After plenty of time trying to run it without trim tabs deployed and with limits on the Autotrim, I found this is my best configuration.

This a different hull and different balance than any boat I have ever owned or driven, its super sensitive to trim angle at higher speeds and also sensitive to how you load the boat. Thankfully it has all the tools to dial it in for your usage and it all works!

Once we figured it all out, we rarely have a problem now and can cruise comfortably at 3000 RPM or if the boat is lightly loaded it will break 50 MPH if you so desire.

Still a very happy boater after several years so what more do I need to say.

We LOVE our Formula ;-)