Speedboat modifications

jlparsons · Post by **jlparsons** » Sun Sep 14, 2008 3:46 pm

Me and my good buddy are planning to build a speedboat some time in the next year (we both had periods of unemployment this year unfortunately so things have been pushed back). I've had this in mind for some time but only recently joined this forum (i'm also planning a sabalo) and saw that dk is on here too, so I thought I'd post this.

Our requirements are:

Suitable for coastal/estuarine use, so reasonable freeboard and self bailing
Range of at least 100miles, 40-50hp outboard engine.
Interior helm and navigator seating for cold weather and rain
space for two to fish
no longer than 17'
trailerable

The DK 16' speedboat looks very promising with some modifications. By scaling up the plans 6%, increasing the freeboard by 100mm and reducing the distance between transom and cockpit by half I've been able to add an enclosed helm to seat two with enough space between for access through a door&hatch combination. I believe the hull shape is suitable for a medium swell (i won't take it out in anything but good weather). I intend to use 9mm plywood with glass inside and out for the cabin top, it'll be s&g throughout but the pillars will be box section and the roof and rear bulkhead will be cross-braced internally. I've increased the height of the cockpit floor by 30mm in addition to the raise caused by scaling the whole design to ensure self-bailing.

What's everyone's opinion on this?

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jlparsons · Post by **jlparsons** » Mon Sep 15, 2008 12:53 pm

No responses... have i made a rookie error here? Please do say if so! I've a fair amount of experience working in wood and metal but have never designed or modified a boat before, so if I'm really going wrong then please do say, criticism will be well received.

This is only a preliminary sketch on cad using the study plans on the dk site.

Post by **jem** » Mon Sep 15, 2008 1:07 pm

There's some power boat folks who visit the forum, but not too many. Chalk may chime in shortly.

Looks like a nice boat if you need some shelter quick. Is it a canvas top or hard top?

I'd say check with Morton to make sure the center of gravity didn't change enough to influence the frame placement and such. But the concept looks well thought out.

jlparsons · Post by **jlparsons** » Mon Sep 15, 2008 1:27 pm

Thanks mate. It's a hard top, but the COG issue does concern me. First stop is to get the opinion of folk who know more than me, then I planned to buy the plans, integrate what's currently only a sketch into the design and make up a scale model. I'd get all the weights proportional and see how she floats.

if you need some shelter quick

Ah... so I see you've been to wales?

Of course, I need to build a sabalo first!

LEE SCHNEIDERMANN · Post by **LEE SCHNEIDERMANN** » Mon Sep 15, 2008 11:02 pm

jlparsons wrote:
if you need some shelter quick
Ah... so I see you've been to wales?

jl,
Breckon Beacons(sp?) with the 2nd Para Regiment. (Her Majesty's finest!)

Lee

hairymick · Post by **hairymick** » Mon Sep 15, 2008 11:31 pm

G'day JL,

I think the lack of response so far is that most of us a paddlers mostly.

One observation I would make is that your seating arrangement will badly limit your visibility if you are travelling in flats or shallow water.

Comfort out of the weather is one thing, but you need to be able to see the water infront of you when travelling at speed.

To this end, I have modified all my power boats so that they are steered from standing position, with a clear and completely unobstructed view of the water infront of the boat.

Sitting low like you have it drawn, will give you a nice view of the horizon while travelling, but little else mate. IMHO

jlparsons · Post by **jlparsons** » Tue Sep 16, 2008 3:42 am

Lee - I'm in Cardiff mate, though I'm an ex-pat (English!) not a local. Been here for 12 years now, family all here, doubt I'll ever go back to England. Where do you kayak? Do you fish?

Hi Mick, the visibility thing was something I was a worried about but had kind of dismissed as the seat is in the same place as the original design. Seeing as there's now a cabin I could stick a second station behind it so you can stand in the cockpit and steer, giving more of a bird's-eye view. What you think? I did toy with the idea before, for use in marinas and when altering position while fishing. With a cable steering system I believe a second helm isn't difficult to do.

I worked out that the boat has to angle back 15 degrees before the prow starts to obscure the view ahead - I think (hope!) that it'll only reach that angle when initially getting onto the plane then should flatten down.