Formula boat porpoising

[ApS]

Originally Posted by XCR-700

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.

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".

[XCR-700]

Originally Posted by ApS

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 ;-)

[ursa minor]

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.

[Taz]

Originally Posted by ursa minor

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.

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.

[Dave R]

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.

[XCR-700]

Originally Posted by Taz

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 dont think so, looks very traditional deep-v

[Bootkie2]

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.

[LIforrelaxin]

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...

[Dave R]

Originally Posted by LIforrelaxin

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.

[Formula260SS]

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.

[VitaBene]

Originally Posted by LIforrelaxin

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...

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.

[Bootkie2]

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.

[8gv]

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

The newer ones are about 2' smaller.

[XCR-700]

Originally Posted by VitaBene

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.

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

[radiocontester]

Originally Posted by Taz

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.

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.