Increasing planing speed for a (fiberglass) Lyman Biscayne

I really like the styling of the Lyman Biscayne but want a boat that can cruise comfortably at 25-30 without having to firewall the engine. The hull is soft chined and and has imitation lapstrake molded in to the fiberglass.
Is there anyway to increase the lift on a hull like this to get it to plane easier/faster? I don’t need 50-60 mph but it would fit our boating MO way better if it could cruise faster than what I’m seeing around the web which is 15-18 mph at 2200-2500 rpm and flat out speeds in the low 40’s.
Strakes? Pads? 4 blade props? Anything?
Thanks

Why not thinking about total weights and distribution?

As Tansl says, lighten the load and /or redistribute what's left.
Another option would be a larger motor... or two.

I presume that your boat is a sistership to the two boats in the links below, which have single inboard shaft drive gasoline engines around 200 hp (?)

https://www.boattrader.com/boat/1972-lyman-biscayne-24-8447223/

1973 Lyman 24' Biscayne https://www.lymanboat.com/collections/lyman-boats-for-sale/products/1973-lyman-24-biscayne

67-LS1 said:

I don’t need 50-60 mph but it would fit our boating MO way better if it could cruise faster than what I’m seeing around the web which is 15-18 mph at 2200-2500 rpm and flat out speeds in the low 40’s.

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Do you know of one in your area for sale, which you could maybe take for a test drive, and see what she is capable of?
If one of these can do 18 mph at 2,500 rpm, then you should still have something left in reserve without firewalling the engine?
It sounds like a flat out speed in the low 40's is not fast enough for you - or is this a typing error?

Yes, those are two samples of what I’m looking at. Inboard, direct drive low-to-mid 200 HP.

IMO, there isn’t a whole lot of weight reduction to be found. The boat is pretty simple. It doesn’t even carry a large fuel load.

Flat out in the low 40’s would be fine because I’ll never do it. I just want to be able to cruise comfortably at 30 mph.

There are none of these that I’ve seen for sale here on the west coast, so my only opportunity to take test ride would be when visiting one of our kids that are all on the east coast.

Would anyone venture a guess as to what a 18 mph @ 2500 rpm boat like this might do at 3000 rpm? 3500 rpm? That’s as fast as I like to cruise at. I know, one could cruise at a higher rpm but I like to think I’m gentle on my equipment.

I’m not against repowering to add some HP. 200-250s seems pretty low by modern standards. A 320 hp small block could shave a little weight and add power. Proper propping for the new power should help too.

But my question is about the soft chine hull. Can anything be (reasonably) done to make this hull plane a little better at lower speeds? Something like what the Conrad TAP Fins can do for pontoon boats?

67-LS1 said:

But my question is about the soft chine hull. Can anything be (reasonably) done to make this hull plane a little better at lower speeds?

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Proven designs work best the way they are.
Modifications are usually guess work at best.
Find a design that meets your needs as is.

I agree, and I’m looking but they’re hard to find.

I confess that I am an old guy. I cannot imagine why one would need to cruise at 30 knots. Why is 30 knots so much more desirable than 20? If your destination is five nautical miles away, then at 30 knots you can arrive there within 10 minutes. At 20 knots you will arrive at your destination with less stress, less fuel consumption, drier, not as noisy, in 15 minutes. You have gained five minutes of time and sacrificed comfort, expense, risk, and wear and tear on your equipment.

If that sacrifice of five minutes is a life changing event, such as rescuing someone with cardiac arrest, the extra speed of response is important. Aside from the necessity to run like hell to get into the harbor before the vicious squall line hits, then 30 is better than 20. Aside from the few real emergency needs, going fast merely satisfies our testosterone drive.

I write this as a former, young gun, APBA hydroplane racer. This old dude has become older ( a lot older) and perhaps a little bit more amazed at how I managed to survive the madness of my youth on fast boats and racing motorcycles. ( please note that, as a matter of maintaneing a modicum of dignity, I did not mention fast women)

I was speaking about 25-30 mph cruise. So 22-26 knots. So not fast-fast, just enough to keep up with the group that we boat with pretty much every weekend.

I'm curios. Do these boats behave fine at 40 knots but just require high engine output% or do they exhibit troublesome ride characteristics.

If the former do the power calcs and see if the modern swap gets into a more desirable rpm Range.

I’ve just been told by a Lyman enthusiast that he believes the Lyman Biscayne is a semi-displacement design and not meant to plane easily. I’m not 100% convinced of that because they will do 40 mph with low 200 hp direct drive inboards. My daughters 82 MasterCraft tournament boat will barely do 40.

Seems pretty quick for soft chine semi-displacement. But if that's what they can do it just really is an issue of power or at least power and transmitting it to the water. Sometimes they can get a little difficult to prop a lot more power.

First and foremost and try and get a solid answer on if they really do the speed you want without getting weird characteristics of ride.

I don't have a lot of fast soft chine experience. My grandad had a soft chine hull that had absurd power but it got really squirelly over a certain speed even with double the hp dropped in. We put the power in it for towing so it didn't matter. But it's ride characteristics with its new found ponies got weird at or above it's manufactured estimated top end.

67-LS1 said:

So 22-26 knots. So not fast-fast, just enough to keep up with the group that we boat with pretty much every weekend.

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What kind of boats are "the group" running?

BlueBell said:

What kind of boats are "the group" running?

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And what is the typical distance travelled?
I presume that this is occurring on San Francisco bay?
I had the pleasure of visiting San Francisco 4 years ago, before Covid kicked off - I can see that SF bay is wonderful for all sorts of waterborne activities.
I did notice though that it always seemed to be a bit choppy when I was there (just for 6 days in July).

Our boating group is my daughter and SIL in their 21 Sanger, a buddy and his family in a Chris Craft 25’ Corsair (Volvo 8.2/duoprop), his son with a 1974 18’ Dan Arena (Volvo/duoprop repower) another buddy with a 1970 24’ Searay Seaman (twin Volvo/duoprop repower), his daughter with a 1985 MasterCraft tournament boat.
All of these boats are on hydra Hoists in adjacent covered berths in the California Delta. Our Tiara is at the same marina but in the bigger boat section.
We have a number of places, depending on wind direction and speed, where we’ll go anchor and swim, bbq, then head back to the marina. Some days we’ll do long cruises to Sacramento or Stockton. The Chris, the Dan Arena and the Searay will go to Napa or Petaluma and the Searay may go to San Francisco once a year or so (to rough for the smaller boats).
My wife and I always feel like we’re bringing up the rear with the Tiara.
So the decision has been made and the Tiara is listed for sale.
I want a classic boat. My wife wants a 28 Chris Corsair. We’ll see who wins this argument…..