Hull Design

[jzangger]

Thanks for the discussion. It brings up some interesting points in the design evolution and is helpful for me in choosing a design to build.

The Glen-L Tiny Titan and Super Spartan both warn they are intended for smooth water while the plan set for the Ben Hur states it is suitable and handles well in rougher water and can accommodate a second rider easily. Based on the previous comments it seems the Ben Hur would be a viable choice over a modern D pickle fork. Now I'm wondering if it would be viable to rework the Ben Hur and put a mild pickle fork and extend the rear a few inches to lengthen the boat a bit? I don't intend to race but do want something safe and enjoyable.

And yes, the Ben Hur has a significant S curve in the bottom.

Thanks for all the information.

Jim Zangger

[pops67g]

Old boats are fun too!

While there is nothing very wrong with the advice being given to this gentleman, pretty much everyone is looking at this as though he is interested in racing. All I see is someone who wants to play with a race inspired boat. Our modern "pickle-fork" boats make fairly lousy play boats (I can't even get in my boats unless someone is holding them up). Pushing him toward Yamato power is SOP these days for a beginning racer, but having no water pump in these motors makes them somewhat undesirable for lake play. I raced a Ben-Hur in D alky hydro back in the 60's and it was very good. It would handle a heavy, fairly powerful engine well. I think having a gearshift, electric start motor might be what this gentleman might be looking to use here and the long cockpit of this old-style boat would accommodate this pretty well.

[B Walker]

Engine options:

If your looking at a modern 4 stroke electric start engine with a service gearbox you can probably get away with a 20HP model. In my experience a 20HP 4 stroke will get you on plane about as well as a 30HP 2 stroke.

The 4 stroke motors make alot better low end power than 2 stroke.

There are no 4 stroke small (under 50HP) racing motors in this country.

BW

[ZUL8TR]

hull design Ben Hur

Thanks for the discussion. It brings up some interesting points in the design evolution and is helpful for me in choosing a design to build.

The Glen-L Tiny Titan and Super Spartan both warn they are intended for smooth water while the plan set for the Ben Hur states it is suitable and handles well in rougher water and can accommodate a second rider easily. Based on the previous comments it seems the Ben Hur would be a viable choice over a modern D pickle fork. Now I'm wondering if it would be viable to rework the Ben Hur and put a mild pickle fork and extend the rear a few inches to lengthen the boat a bit? I don't intend to race but do want something safe and enjoyable.

And yes, the Ben Hur has a significant S curve in the bottom.

Thanks for all the information.

Jim Zangger

I would not pickle or change the dimensions of the Ben Hur. For non racing use it should provide a reasonable ride if you do not overload it too much. If you do build it I suggest that you stay away from fir plywood that grain checks to easly unless you fiberglass it. Okume ply is preferable for a more stable grain and it finishes better but more costly. The Glen L and Clark Craft kits probably use fir plywood. If Okume used do 6 mm bottom, sides, main girders and gussets and 3mm deck and use epoxy glue.

As far as power you might want to consider a standard lower unit for more reliable operation since race engines will definately be harder to get on plane especially if 2 passangers. Just adjust the transom height to accomodate the longer shaft dimension.

[jzangger]

From pops67g

"While there is nothing very wrong with the advice being given to this gentleman, pretty much everyone is looking at this as though he is interested in racing. All I see is someone who wants to play with a race inspired boat. Our modern "pickle-fork" boats make fairly lousy play boats (I can't even get in my boats unless someone is holding them up). Pushing him toward Yamato power is SOP these days for a beginning racer, but having no water pump in these motors makes them somewhat undesirable for lake play. I raced a Ben-Hur in D alky hydro back in the 60's and it was very good. It would handle a heavy, fairly powerful engine well. I think having a gearshift, electric start motor might be what this gentleman might be looking to use here and the long cockpit of this old-style boat would accommodate this pretty well."

You nailed my thoughts exactly, and from someone who is actually familiar with the Ben Hur! I know it's an old design but it sounds like this would be a good stable boat large enough to handle my desires. If I ever would want to "race", and I use the term loosely, I could do so in the vintage category.

At one time I owned an old 50hp Mercury but sold it with the aluminum runabout. Something like that or most any other reasonably priced used engine in the 40 to 50hp range sounds like it would be a good match for this boat. And yes, electric start on that size would be desirable.

Thanks for the help and any other insight you might have on the old Ben Hur would be appreciated.

Jim Zangger

[jzangger]

I would not pickle or change the dimensions of the Ben Hur. For non racing use it should provide a reasonable ride if you do not overload it too much. If you do build it I suggest that you stay away from fir plywood that grain checks to easly unless you fiberglass it. Okume ply is preferable for a more stable grain and it finishes better but more costly. The Glen L and Clark Craft kits probably use fir plywood. If Okume used do 6 mm bottom, sides, main girders and gussets and 3mm deck and use epoxy glue.

As far as power you might want to consider a standard lower unit for more reliable operation since race engines will definately be harder to get on plane especially if 2 passangers. Just adjust the transom height to accomodate the longer shaft dimension.

That answers yet another question! The standard long shaft engines would be fine for my purpose if I adjust the transom to accommodate the extra length. Then the question is - where should the prop shaft center be in relation to the hull bottom? Will I still want some of the top half of the prop to be out of the water as in a race configuration?

I used phillipine ribbon stripe mahogany for the decking on my previous small boat and it seems fine. For the sponsons and bottom I believe I just used marine plywood but don't recall if it was fir or the okume. I know I used the weldwood glue but the T88 epoxy system is probably the one for today's use.

Thanks again for all the great advice.

Jim Zangger

[jzangger]

Just guessing, is the reason for the short shafts to keep the center of gravity lower and maybe reduce some weight?

Jim

[Yellowjacket]

More motor options

Or you could just put an older 4 cyl Merc on it. You can get a decent Merc 400or Mark 58 for about $500 and if you make the motor board taller so you can use the stock short shaft version and a service gearbox (as opposed to the quicksilver lower unit that the boat is probably designed for) it would work. If you don't jack it way up high it will probably run about 50 mph with two persons aboard. If you put a real serious prop on it would probably be faster, but you can't put it high enough to go really fast unless you put in a low water pickup anyway. Plus, if it doesn't smell like burning oil, it isn't a real boat...

Just my random thoughts...

Actually what this is starting to look like is a pretty good representation of a classic D boat that you would have made 30 years ago but with a couple of mods to make it into something that you can live with and have fun on a lake (a service lower unit). Wouldn't be a race boat, but it would be pretty neat.

Sounds like a lot of fun, keep us posted on what you decide to do.

[Yellowjacket]

Just guessing, is the reason for the short shafts to keep the center of gravity lower and maybe reduce some weight?

Jim

For sure don't want to use a long shaft engine. Stick with a short shaft. The layout of the design was probably for an engine with a quicksilver lower unit which is shorter than a short shaft. You would have an engine that stuck up to outer space if you use a long shaft motor and you already are going to have more weight up there with a gearbox and an electric start and the longer than a racing mid section on it, so a short shaft version is what you want.

[Kev43V]

the most important part.... HAVE FUN!

[Silas_53A]

yeah, I would definitely go with a short shaft, specially if you go for the 50hp range. having all that weight an extra 10" higher is much more unsafe/unstable.

[jzangger]

Thanks for all the responses. It has really given me some good insight as to what direction I need to go. Looks like the Ben Hur as designed with a short shaft stock Mercury in the 40-50hp range. I also appreciate the information on the evolution of the hydroplane designs. This has really been helpful and I thank you all.

Jim Zangger

[ZUL8TR]

Ben Hur

That answers yet another question! The standard long shaft engines would be fine for my purpose if I adjust the transom to accommodate the extra length. Then the question is - where should the prop shaft center be in relation to the hull bottom? Will I still want some of the top half of the prop to be out of the water as in a race configuration?

I used phillipine ribbon stripe mahogany for the decking on my previous small boat and it seems fine. For the sponsons and bottom I believe I just used marine plywood but don't recall if it was fir or the okume. I know I used the weldwood glue but the T88 epoxy system is probably the one for today's use.

Thanks again for all the great advice.

Jim Zangger

If you go with the standard fishing engine with the standard shaft length (not the extra long shaft) I would make the transom height such that the anti-cavitation plate is at the hull bottom. Then you would at least have a setup (while not the fastest) that will definately have water cooling pickup, easy out of the hole, good acceleration and reasonable speed without cavitating the prop that is not designed to ventilate like racing setup props that are fully ventilated. Also you can still raise the engine with shim sticks and see what results but be mindfull of the engine cooling and cavitating.

Since the hydro and passangers will be relatively light with less water resistance than a fishing boat my guess is that you will be able to use a prop that has more pitch and less diameter than the standard prop that comes on these fishing engines thus higher speeds. A tachometer and speedometer will tell that tale.

Marine plywood is usually fir. Stick with the marine grade ribbon mahogany but ocume is a lighter choice, compare prices.

Racing lower units were made shorter to allow the ventilating props to be raised without having the power head excessively high and reduced water drag and allow more prop pitch for greater speed. Water cooling pickups were also lowered to allow cooling water in.

Good luck, keep us informed with your progress and questions, show pictures and have fun.