Back to the drawing board......

[Willallison]

Ok, so it's back to the drawing boards as far as the speed profile of Option One is concerned.
Before anyone commences a new poll, perhaps we should hear some points of view from all our participants - and especially all of those out there who have up to this point viewed but not submitted their ideas......
Do we, for instance, accept the other decisions taken since the speed poll - such as accomodation & mono v cat - and ensure that our speed fits in with those decisions, or do we come up with a new speed profile, then re-assess evrything else as well?

[duluthboats]

Here we are.

1 Coastal hopping for a week
2 Trailer able
3 Range 300 miles
4 Crew, 2 minimum
5 Price range, under 50K US, for home built.
6 Must be able to carry on a normal conversation at 3/4 throttle

Below is the winner for LOA.

29'-32'


Above is stuff we have voted on, below is a list from Will that summarizes what is needed on a boat like Option 1. Sorry for repeating this again but I want all of us to be on the same page. The list below is debatable, as well as the reassessment of the speed.


1. We have a minimum crew of 2, so we need at least 2 (preferably permanent) berths and possibly two more convertible. The only time I'm prepared to crawl into bed is when I've had too much to drink, so I want at least near standing headroom at the foot of the bed.
2. Full standing headroom is an absolute necessity in all "living" areas - particularly if you're going to spend up to a week on board. A hardtop is not the be all and end all to me - well designed canopies, with lots of 'clears' work very well. Of more importance is to be able to see out when both sitting or standing.
3. Cooking and eating facilities should reflect the boats expected crew - nothing seems more absurd to me than all those "med-style" boats with huge galley's, four staterooms - but nowhere to sit and eat. I want to be able have 4 sit for dinner and a galley big enough to prepare the meal on. Stowage / refrigeration should be comensurate with our 1 week cruise.
4. Show me a woman who doesn't want an enclosed wc with shower and I'll show you one who's never spent a week away on a small boat with a couple of other people......
In many places now, that necessitates the use of a holding tank.
5. 12 volt power for everything. Generators have no place on a boat this small which has light weight as one of its primary requirements.
6. I cruise with two dogs (dalmations) - I need a dinghy! We use an 8 foot inflatable on my 27 ft Searay. It sits on the boarding platform (another absolute necessity) and is both light and easily managed.

Gary

[Portager]

I'd like to make a few suggestions or comments.

Engine(s): I think the trade-off between inboard versus outboard should be given some consideration in regards to this application. It has been my observation that cabin cruisers generally prefer inboards over outboards. Maybe because it is easier to use the inboard to heat water and if the boat has a shower, then the next requirement is a water heater. I have also noticed that salt water boats that are going to be left in the water for a period of time tend to favor inboards over inboard/outboard and outboard drives. Perhaps due to corrosion issues? One additional advantage of an inboard is the engine can be placed at or near the boat CG, which minimizes trim problems when switching from the small to large engine option. Placing larger mass items near the CG also reduces the boats pitch moment of inertia, allowing the boat to respond quicker and reducing dynamic loads in the structure.

Beam: What is the definition of trailerable? A few states only allow 8' beam, while most allow 8' 6". With a wide load permit
you can go even larger, but with increasing difficulty. I have found that >8' but <10' 1" requires a wide load permit, but has very few
additional restrictions. For example most states only allow wide loads over 10' 1" to travel from 1/2 hour before sunrise to 1/2
hour after sunset. Under 10' 1" can travel at any time. In addition some loads over 10' 1" require a pilot car on some routes. Increasing the beam from 8' 6" to 10' 0" provides at least 17% greater interior space.

Height: I have researched the maximum height for most states in the USA. I found that 13' 6" was good for every state I thought I'd ever go through.

Weight: The selected tow vehicle will define the combined boat and trailer weight limit. See the tow ratings at http://www.trailerlife.com/towratings/tr_index.cfm. The boat weight limit will be the tow vehicle limit minus the trailer weight.
Therefore it is important to use a strong but light weight trailer.

Trailer materials: Painted steel trailers are generally adequate for fresh water but not for salt water. For salt water trailers are generally galvanized steel or aluminum. Galvanized steel is cheaper but aluminum is lighter.

Trailer type: gooseneck trailers allow better load distribution, tighter turning radius and since the hitch can carry 25% instead of 10% of the gross trailer weight, they reduce the trailer axial loads and improve tow vehicle traction. They also cost most and can't be hitched to the front of the tow vehicle for easier launching.

Cheers;
Mike Schooley

[duluthboats]

Glad to see you are still with us Mike. I should have brought these to the top also. One thing we in the US have to remember is that this is an international forum. Option 1, will be an international boat. ( remember the Ford Escort :D)

http://www.boatdesign.net/forums/showthread.php?s=&threadid=549

http://www.boatdesign.net/forums/showthread.php?s=&threadid=522

Gary

[Willallison]

This is a little off subject, but I thought Mike - or someone else for that matter - may be able to help me out with a trailer question.
What's a fifth wheel?

[8knots]

Hey there fellow boat nuts!
Sorry have been away for awhile but spring in Alaska brings long days and lots of catch up work! I must admit I have no idea where we are but am glad to see you all are still carrying the flag.
I will do some reading up and see if I can contribute allthough time is limited. Where is POLARITY? I would like to see more of the project PORTAGER is working on. Anyway glad all is well, Good spring to all!!!!!!!! 8Kts

[Willallison]

Ok, I can hold my silence no longer - progress seems to have stalled somewhat on coming up with a speed range for Option One.
These are the suggestions made in our previous poll:

Speedy

1. Max speed 25 - 28 knots
2. Max Cruise 20 - 22
3. able to maintain planing down to 12 knots and economical to operate throughout its speed range

More Speedy

1. Max Speed 45+
2. Cruise 30 - 40
3. Economical at cruise as well as at displacement speed

Definitely Not Speedy

1. Max 7
2. Cruise 5 - 6


Now surely, there must be some comment out there - perhaps some more options - adjustments to those already put up......anything.....

Previous discussions can be seen here http://boatdesign.net/forums/showthread.php?s=&threadid=567

[tom28571]

Will,

I have been waiting for someone to put forth some data that would support the longer and more speedy option with all the facilities that many seem to want.

For instance, assuming a monohull, what is the minimum cruise speed at which the boat remains in an economical planing mode?


At some point, there has to be some math to support the wish list. I think that much of this is possible, but that is just speculation on my part.

[Willallison]

I guess that depends a lot on hull form and weight. What I had in mind was something with around 18 to 20 degrees of transom deadrise. This, of course is not a true deep v but would assist in providing lift to allow a relatively lightweight boat to come back to something in the order of 18 to 20 knots without falling off the plane.
By having less deadrise you compromise the rough water capability of the craft at high speed, but I think the reality is that very few people want to travel for any real length of time at 40 knots when it is rough - the ability to throttle back is very important.
I see a very fine entry as assisting in slicing through surface chop. Of course this can bring about its own set of problems when running with a sea, but many sportsfishing boats accomplish an acceptable compromise.
The result of all that, to my mind, is a craft capable of zipping along quickly when conditions permit but still capable of slowing down when things get uncomfortable.
As far as the maths goes, I'm only a beginner at this designing game - you're infinite wisdom will have to guide us there!!:D

One more thing - 175 of you had taken a peek at what's written in this thread alone when I last looked. PLEASE give us your opinion.......

[duluthboats]

That 175? I peeked 150 myself. :D So option 1 is on the rocks and the tide is going out. NOT!! Sorry Tom, but I can't do the numbers. I'm sure we could come up with something that would work. (he's guessing again) I'm just not sure if it would be a boat or just a piece of engineering. I'm in favor of Pauls idea, and maybe drop the top end a little.

Will, a fifth wheel is the same as a goose neck trailer.

8knots, hang with us, we need you.

Gary

[duluthboats]

For the new poll, one choice:
Max speed 35knots
cruise at 25-30 knots
with smaller motor on same boat drop the above by 5 knots.
Gary

[Polarity]

yes indeed!

[Willallison]

dropping the top speed by 10 knots does have a significant effect on the amount of power required.
For instance, depending on which Crouch Constant you use (see http://boatdesign.net/forums/showthread.php?s=&threadid=615 ) then a boat of approx 1800kg would require somewhere between 135 & 220 hp to achieve 35k. The same boat to reach 45k will need 220 to 360 hp. ( In both cases, the upper end of the spectrum seems more realistic)
This brings it firmly back into the single engine requirement area - a significant point given our budget.......

[Portager]

We just returned from vacation, if you can call driving 5,000 miles in 15 days a vacation, so I'll try and answer the "fifth wheel" trailer question.

The term "fifth wheel" is derived from the "fifth wheel" hitch. Here is a definition from http://www.hitch-web.com "Fifth Wheels are hitches in the bed of your pickup that include a plate, like on a big rig, whereas a gooseneck is a ball in the bed that gets mounted right to the frame. "

Most people refer to "Fifth Wheel Trailers" and "Gooseneck Trailers" generically (and erroneously) as fifth wheels or fivers.

Conventional trailers with a ball hitch mounted at the rear bumper are commonly referred to as "tag along" trailers.

The main benefits of a "fifth wheel trailer" are stability, weight distribution and turning radius.

Stability: the pivot point is directly over the rear axial so it de-couples the interactive dynamics of the tow vehicle and trailer (you don't see fifth wheel trailers fish-tailing like tag along trailers sometimes do).

Weight distribution: Fifth wheel and gooseneck trailers can apply 25% of the trailer weight to the hitch, where as the tag along limit is 10% to 15% and large trailers need to stay closer to the 10% limit. For a 20,000 trailer this equates to 5,000 lbs versus 2,000 lbs on the hitch. For a tow vehicle with 4,000 lbs on the rear axial empty, the loaded weight is 9,000 lbs versus 6,000 lbs. This means that the fifth wheel trailer has 50% better traction. In addition the trailer axial load is 15,000 versus 18,000 lbs so you will need bigger axials and tires.

Turning radius: With a fifth wheel trailer the tow vehicle can turn greater than 90 degrees relative to the trailer but a tag along will be limited to 60 to 75 degrees. This means the fifth wheel trailer turning radius is equal to the hitch to center axial distance however you need to keep in mind that these tight turns produce high side loads on the tires. I like to keep a bag of fine sand on board to use as a lubricant.

The advantages of a tag along trailers are you retain the use of the truck bed, you can launch using a front hitch (provided your tow vehicle can accommodate the hitch load on the front) and the trailer is shorter.

Hope this answers the question.

Cheers;
Mike Schooley

[Nomad]

Sorry I have been moving........................................