Low speed planing woes

[twiggy2cents]

So, I love my boat. It is a great first boat, but I dont know if it is a bad hull design or what. According to GPS speed it falls off plane at 22 mph. The boat is a 89 Arriva 19.5 footer with a 350. This is with me at the captains seat and two small people that in the back that say they will not sit up front. I dont wanna buy a fat sac or hydraulic trim tabs. Which would be more desirable, sand bags in the bow or smart tabs or another option? Will smart tabs screw up the wake?

Regardless of the answer, I dont have the money for smart tabs at the moment(just bought a bimini top), I do have a hydrofoil that I took off last year though. I know the general consensus is that they are bad on a an I/O, but I need something to get my by until probably next year.

 

[JoLin]

Re: Low speed planing woes

My 21' Pro-Line outboard suffered the same. It was stern heavy, like your boat. A 4-blade prop helped, and Smart Tabs helped more. The combo dropped my minimum planing speed from the low 20's to mid-high teens. About 5 mph difference. It's hard to correct without spending some money.... so I'd try the hydrofoil. You have nothing to lose, and they do sometimes work.

My .02

 

[Mi duckdown]

Re: Low speed planing woes

Are you using your power trim correctly?

 

[JimS123]

Re: Low speed planing woes

So, I love my boat. It is a great first boat, but I dont know if it is a bad hull design or what. According to GPS speed it falls off plane at 22 mph. The boat is a 89 Arriva 19.5 footer with a 350. This is with me at the captains seat and two small people that in the back that say they will not sit up front. I dont wanna buy a fat sac or hydraulic trim tabs. Which would be more desirable, sand bags in the bow or smart tabs or another option? Will smart tabs screw up the wake?

Regardless of the answer, I dont have the money for smart tabs at the moment(just bought a bimini top), I do have a hydrofoil that I took off last year though. I know the general consensus is that they are bad on a an I/O, but I need something to get my by until probably next year.

They are all bad hull designs now. They don't make them like they used to. A 19 woody back in 1950 didn't need any help.

The general consensus is that foils they are better than sliced bread. Why would 147,298,546 of them be in use right now as we speak? Why did you take it off? Because you HEARD it was bad, or because taking it off fixed your problem?

Don't add more weight, that'll just slow you down. Foils are meant for stern heavy boats.

 

[twiggy2cents]

Re: Low speed planing woes

I've heard that foils are bad for I/O's due to the foil not coming out of the water when planed. And yes that is with trim full down.

 

[H20Rat]

Re: Low speed planing woes

The general consensus is that foils they are better than sliced bread. Why would 147,298,546 of them be in use right now as we speak? Why did you take it off? Because you HEARD it was bad, or because taking it off fixed your problem?

Don't add more weight, that'll just slow you down. Foils are meant for stern heavy boats.

Who's general consensus? At least in most experienced boating circles, foils are best placed at the bottom of the lake, and no where close to a boat!

There are very, very few cases where foils are a good idea. This isn't one of them.

 

[Mi duckdown]

Re: Low speed planing woes

Twiggy. that is your problem. trim down to get the boat going, then trim up to keep it on plane. Play with the trim.
Not a fan of hydros.

 

[crabby captain john]

Re: Low speed planing woes

Back in the 80s my boating friends told me I was wasting time and money but I listened to the hype and advertising and wasted my time and money. They are most beneficial by keeping people busy installing and uninstalling them and not fighting with their wife. Sold mine at a flea market-- it could have been on and off 25 - 30 boats by now unless someone with a short temper put it where it really belonged, the landfill.

 

[twiggy2cents]

Re: Low speed planing woes

Twiggy. that is your problem. trim down to get the boat going, then trim up to keep it on plane. Play with the trim.
Not a fan of hydros.

I thought trimming up only helps how the boat rides while planed. If I am at the breaking point for planing, wouldn't trimming up raise the bow and help it fall off plane?

 

[JoLin]

Re: Low speed planing woes

Twiggy. that is your problem. trim down to get the boat going, then trim up to keep it on plane. Play with the trim.
Not a fan of hydros.

Optimal use of trim helps boat handling overall, but IMO it won't solve the OP's issue. His minmum planing speed (22 mph) is fairly high. That's the norm for a short boat with a lot of weight in the stern. Tabs will help the most. A prop that provides more stern lift (4-blade, like a Solas Rubex) will also help to a lesser extent. The two together will give him as good as it's gonna get for about $400. BTDT.

There's no harm in his trying a foil that he already owns, though I don't think it'll do what he wants. The holes are drilled- slap it on, try it, take it off if he doesn't like it. It won't hurt anything.

My .02

 

[JimS123]

Re: Low speed planing woes

I've heard that foils are bad for I/O's due to the foil not coming out of the water when planed. And yes that is with trim full down.

The foil on my I/O has been there for 28 years. It meets my requirements and I'm satisfied with the performance. I "heard" what "they" said too - that was AFTER I had about 15 years of personal experience under my belt.

My son's cuddy has one too and he won't take his off either.

 

[JimS123]

Re: Low speed planing woes

Who's general consensus? At least in most experienced boating circles, foils are best placed at the bottom of the lake, and no where close to a boat!

There are very, very few cases where foils are a good idea. This isn't one of them.

In my area I see a huge percentage of the boats with them on and when I speak to the owners they usually have positive things to say. I believe the first one came on the market in the 1980's. The fact that they are still in business and even other competitors have come out with their versions speaks volumes. You can fool some of the people some of the time but products that truly are useless don't stand the test of time.

"General consensus" is probably a poor term here - it all depends on the group you're talking too.

I've put 5 of them on since about 1985. All are still in use today except 1. The only boat that it didn't work well on was a 14' tinny that was overpowered.

As far as the OP's question, in my opinion his type boat is a textbook example of where a fin would be useful. But only he can decide. Since he already has one, he can test both ways and prove or disprove it for himself. Nothing like data!

 

[metriccrescentwrench]

Re: Low speed planing woes

....

"General consensus" is probably a poor term here - it all depends on the group you're talking too.

I've put 5 of them on since about 1985. All are still in use today except 1. The only boat that it didn't work well on was a 14' tinny that was overpowered.

As far as the OP's question, in my opinion his type boat is a textbook example of where a fin would be useful. But only he can decide. Since he already has one, he can test both ways and prove or disprove it for himself. Nothing like data!

I've always wondered how many of the people who bash hydrofoils have ever tried them. The thing is, they're not going to solve every handling problem for every boat out there. But in a lot of cases they'll definitely get you on plane at a slower speed with less bow rise. I've got a fish-n-ski with a hydrofoil, it's great on that boat. Jumps right up on plane almost instantly. I don't really have a need on the Checkmate as it's got plenty of power to raise the stern without any help. As far as this discussion goes, twiggy ought to go ahead and see what happens with one. Not gonna' hurt anything to try.

 

[emilsr]

Re: Low speed planing woes

I'm not a fan of 'foils either (and I have tried them), but in this case it may help. They do provide low speed lift at the transom and MIGHT help lower the minimum planing speed.

A neutral or stern lifting prop will help as well.

Both of these solutions will be detrimental at speed, but if low planing speed is all he's after these are two good solutions.

I resolved this on my last runabout with a combination of neutral lift prop and Lenco tabs; dropped minimum planing speed from about 22 down to 17 or 18. Not a cheap solution, but worth considering as the budget permits.