Trojan Boat Forum

Vic wrote:
What do you think about my prop size and pitch?

need some input from the mid cabin guys
I rarely take it up to WOP. But, I am pretty sure that the Crusaders will wind to 4,100. I usually back off at +3,500, as the FloScans are pegged at that point!

WOT should be about 4,400 RPM
I understand the theory, behind the Delta Conic design - not sure, why more boats did not have this bottom. I remember when Trojan and Larsen first started selling boats with this feature.

It's a Harry Schoell patent.
Love the way that my boat performs in a head sea - very soft; and the down-sea tracking is a pleasure - set the auto pilot and forget it.
I checked my tabs the last time that I hauled and actually tuned them up a little.

Set your RPM at a speed, say 15 kts with the tabs complety retracted.

Bump the tabs a bit, incrementally and wait a few seconds to see if your GPS shows a bit of a speed increase. at some point the increase will turn into a decrease as you put more bow down.

The highest speed at that set RPM is your best tab angle for that given speed.

Different speeds and sea conditions will require different tab settings.
This spray deal has been a situation for all ten years that I have owned the boat. Just never thought about doing anything about it soon enough to rectify the situation at haul-out. Again, on 2/11 my boat will go on the ways.

Tell us more about the spray/wet issue.

I think perhaps while you ARE on plane, you are not getting up to th emost optimum running angle.

Planing hulls are designed to climb up and run on top of the water. While these boats will come on plane at 12 KTS, 12-14 kts will not produce the optimum runnning angle.

At slower speeds I doubt that the tabs will have the same effect as at 16-20 kts.

We really need to hear from some of the nmid cabin guys on this.

RWS

published boat review quote

=======================================
Schoell's patented DeltaConic hull design has 18 inch wide horizontal chines that run from bow to stern on either side. In between the chines, the modified-V hull is deep at the bow and flatter toward the stern.

It all works remarkably well. The 10 Meter's wide body, combined with the wide chines, provides a remarkably stable and dry ride. Steering response isn't especially quick, but the boat feels solid and secure when those wide chines lock in for a turn.
==================================

Ok - thought you ran with fixed tabs - and the auto-pilot to boot.

Don't know your hull enough to help -will defer to others ... good luck!

Some day - Buddy Davis = dry hull!

I have played with the tabs over the years.
She seems to like full tab at about 2,850 R's - definitely planeing and the fuel consumption is reasonable. But, the GPS says that we are only traveling at about 14 mph. Actually, I have found that, if you divide the RPM's by 200 that you invariably arrive at the speed of my boat.
But, I will mess around with the tabs a little next weekend and see, what happens.

let's see if this link works -

It's an article that appeared in POPULAR SCIENCE in August, 1982

There is some info here regarding the design and the DRY ride.

RWS
================================

http://books.google.com/books?id=kz8x2P ... an&f=false

Very cool article. I enjoyed reading that and many others in that file! Thanks!

No doubt a revolutionary design.
Still puzzles me, why that more builders do not use this bottom today?

Because there are many other good hulls out there some better some not as good , and there is no perfect hull , My F36 hull take less hp to move at a given speed then a DeltaConic hull there by faster and burns less fuel . But will not ride as well in bad seas , so like every hull it is a compromise .

If you use a DeltaConic hull you have to pay the patent holder for doing so may not be cheap

Enjoyed the article! Thanks!


Trojan 10meter picture from August 1982 Popular Science article

Ref: http://books.google.com/books?id=kz8x2P ... an&f=false

Harry Schoell's original March 18, 1980 Delta-Conic hull US Patent # 4,193,370 :







ref: http://www.wikipatents.com/US-Patent-41 ... ull/Page-1

item #20 & 21 contribute to the dry ride.

So back to the original post - spray knockers -

It is my opinion that the vessel in question is not getting up on plane enough to render the chine lip effective.

As an Intl ownner it's interesting to be a passenger while on olane watching the water move away from the boat.

Just my own $0.02

RWS

Hi guys, RWS pulled me out of hibernation to comment on this thread.
I have a 1986 Mid cabin. I routinely hit 3-4' waves in teh bay near Warwick light, Narragansett Bay. Generally, I don't get much water in or on the boat until the wind hits 20Kts or so. Then I get wind spray. In any case, I am not close to burying the bow and the water moves away from the boat pretty well.

I tend to run at about 2900-3000 RPM, at 14-16 kts, depending on condition. The mid cabins definitely run a little less efficient than the express. Fuel load is a big factor. I will be increasing the size of the trim tabs this year to get me a little more lift to get on plane a little better. That should allow me to run at 2800 RPM.

I don't have flow scans so I can't give you a great reading on sweet spot. It's more on how the boat feels. My WOT is about 4300-4400.

At 2800 RPM, you are doing 14 MPH whcih equates to about 12.5 knots. If you run the boat a little higher, say 3000 or 3100 RPM, how is the water spray? Even at 3000 RPM I have the tabs fully in. My bow angle l is still abotu 6 degrees. I think RWS posted somthing a whiel back that these boats are designed to run at about 4.5.

I'd have to look at my props to give you the pitch, but they are perfectly in the WOT range. I run three bladed nibrals.

I ran the boat in 6-8 footers at about 12 knots in 25knot winds one spring. I gto a decent amount of wind spray (refreshing when the water temp was about 55F, ) but never came close to burying the bow or taking any sort of wave in the cockpit. I tend to run quartering to waves, so should be similar.

Seems like your experiences are somewhat similar to mine, except for the fact that at about 2,850 RPM's my speed is only about 14 MPH - not knots.
In today's world of +4 buck gas, you probably should not get Flo-Scans. It would probably cause you to question taking your boat out of the slip to see the money going out your exhaust pipe!

I'd be willing to wager that FOR WHATEVER REASON Vic's boat is NOT getting up on p[lane enough to take advantage of the dry ride design feature.

Forget about the RPM's for a moment - this is about speed and the lift that the props contribute to th erunning attitude.

Getting more of the hull up and out of the water should do two things:

1) decrease the wetted surface area

2) increase effeciencies

3) make the hull do it's job of deflecting the water better - as designed.

RWS

I hear you on the gas, but gas is one of my lower expenses owning the boat so ya just deal with it.